To answer this question, you need to understand the concept of loop testing. Loop testing is a control structure testing technique that focuses on testing the validity of loop constructs.
Let's go through each option to understand why it is correct or incorrect:
Option A) Rely basis path testing - This option is incorrect because loop testing is a separate testing technique and is not reliant on basis path testing.
Option B) Exercise the logical conditions in a program module - This option is incorrect because loop testing specifically focuses on testing the validity of loop constructs, rather than exercising logical conditions in a program module.
Option C) Select test paths based on the locations and uses of variables - This option is incorrect because loop testing does not specifically select test paths based on the locations and uses of variables. It primarily focuses on testing the validity of loop constructs.
Option D) Focus on testing the validity of loop constructs - This option is correct because loop testing is a control structure testing technique that specifically focuses on testing the validity of loop constructs.
The correct answer is D. This option is correct because loop testing is designed to specifically test the validity of loop constructs.