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 subjective and does not provide clear criteria for verification or validation.
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 any system will contain zero faults. It is not feasible to test for the absence of faults.
Option C) The response time shall be less than one second for the specified design load.
This requirement is testable. The response time can be objectively measured and compared against the specified criteria of being less than one second.
Option D) The system shall be built to be portable.
This requirement is not testable because "portable" is not clearly defined and does not provide specific criteria for verification or validation.
The correct answer is Option C. This option is testable because the response time can be objectively measured and evaluated against the specified criteria.