To call a function named "myFunction", you need to use option A, which is "myFunction()". This syntax will execute the code inside the function and return any value that is specified in the function.

Option B, "call myFunction()", is incorrect because it is not valid syntax for calling a function in most programming languages, including JavaScript.

Option C, "call function myFunction", is also incorrect because it is not valid syntax for calling a function in most programming languages, including JavaScript.

Option D, "function myFunction", is incorrect because it only declares the function, but does not actually call it. To execute the code inside the function, you need to use the function name followed by parentheses, like in option A.

Therefore, the answer is: A. myFunction()

To solve this question, the user needs to understand the purpose of WebServices.

WebServices are designed to enable communication between different software applications, regardless of their programming languages, hardware, and operating systems. They are intended to solve interoperability problems, enabling different applications to exchange data and services seamlessly.

User interface, complexity, and firewall traversal are not the primary problems that WebServices are intended to solve. They are typically addressed by other technologies.

Option B, User Interface, is not intended to be solved by WebServices. User interface refers to the way users interact with software applications. WebServices are not designed to handle user interfaces; instead, they focus on the exchange of data between applications.

Option A, Interoperability, is the primary problem that WebServices are intended to solve. They enable applications to communicate with each other, regardless of their platforms, programming languages, and data formats.

Option C, Complexity, is not a problem that WebServices are specifically designed to solve. However, WebServices can help reduce complexity by providing a standardized way of exchanging data between applications.

Option D, Firewall Traversal, is not the primary problem that WebServices are intended to solve. However, they can help resolve this issue by using standard HTTP and XML protocols that can pass through firewalls more easily.

Therefore, the correct answer is:

The Answer is: B. User Interface

To solve this question, the user needs to understand the concept of XML elements and attributes, as well as the purpose of ensuring unique identities for these elements and attributes.

Explanation of each option:

A. named pipe: A named pipe is a method of inter-process communication in which two or more processes can communicate with each other by writing and reading from a pipe. This option is unrelated to the concept of unique identities for XML elements and attributes.

B. fully-qualified domain name: A fully-qualified domain name (FQDN) is a domain name that specifies the exact location of a resource on the internet. This option is unrelated to the concept of unique identities for XML elements and attributes.

C. Multiprotocol Label Switching: Multiprotocol Label Switching (MPLS) is a routing technique that directs data packets along predefined paths within a network. This option is unrelated to the concept of unique identities for XML elements and attributes.

D. namespace: A namespace in XML is a mechanism that allows elements and attributes to have unique identities. It ensures that element and attribute names are globally unique, preventing naming conflicts. This is the correct option for ensuring unique identities of XML elements and attributes.

Therefore, the correct answer is:

D. namespace

To create a horizontal rule in HTML, we can use the <hr> tag.

Now let's go through each option and determine if it is the correct answer:

A. <b>: This tag is used to make text bold, not to create a horizontal rule. So, this option is incorrect.

B. </b><p>: This tag is used to create a paragraph, not a horizontal rule. Therefore, this option is incorrect.

C. <br>: This tag is used to insert a line break, not a horizontal rule. Hence, this option is incorrect.

D. </p><hr>: This tag is specifically used to create a horizontal rule. So, this option is the correct answer.

Therefore, the correct answer is D - <hr>.