To answer this question, we need to understand what makes a requirement testable. A testable requirement is one that can be objectively verified or validated through testing.
Let's go through each option to understand why it is correct or incorrect:
Option A) The system shall be user friendly - This requirement is not testable because "user friendly" is a subjective term and can vary from person to person. It is difficult to measure or quantify what makes a system "user friendly."
Option B) The safety-critical parts of the system shall contain 0 faults - This requirement is not testable because it is practically impossible to guarantee that there will be zero faults in any system. Even with extensive testing, it is unlikely to achieve a fault-free system.
Option C) The response time shall be less than one second for the specified design load - This requirement is testable because it provides a clear and measurable criterion. The response time can be objectively measured and compared against the specified limit of one second.
Option D) The system shall be built to be portable - This requirement is not testable because "portable" is a vague term and can be interpreted in different ways. It does not provide any specific criteria or measurable attributes to determine if the system is portable or not.
The correct answer is Option C. This option is testable because it provides a clear and measurable criterion for the response time of the system.