To answer this question, we need to understand the concept of an unconnected lookup.
An unconnected lookup is a type of lookup transformation in Informatica PowerCenter that is not directly connected to a source or target. It is used to perform lookups on a small set of data or to perform complex lookups that cannot be achieved using connected lookups.
Let's go through each option to understand why it is correct or incorrect:
Option A) It does not contain a return port - This option is incorrect. An unconnected lookup does contain a return port. The return port is used to return the result of the lookup operation to the calling transformation or expression.
Option B) Executed for every record passed - This option is incorrect. An unconnected lookup is executed for each record passed to it. It performs a lookup operation for each input record individually.
Option C) Works only when the lookup function is called - This option is correct. An unconnected lookup is not automatically triggered like a connected lookup. It needs to be explicitly called using the LKP expression or LKP transformation in Informatica PowerCenter.
Option D) All of the above - This option is incorrect. Option C is the correct answer, so not all of the options are true.
The correct answer is C) Works only when the lookup function is called. This option is correct because an unconnected lookup is not automatically triggered and needs to be explicitly called using the LKP expression or LKP transformation.
Therefore, the correct answer is C)