Which of the following is true about the relationship between statement coverage and decision coverage?

The assertion that 100% decision coverage guarantees 100% statement coverage is true due to the relationship between the two types of coverage metrics. Decision coverage measures whether each point of decision (such as branches in conditional statements) in the code has been executed, whereas statement coverage focuses on whether each individual statement in the code has been executed at least once.

When you achieve 100% decision coverage, it means that all possible outcomes of the decision points in the code have been tested. Since exercising every decision implies that the statements leading to both the true and false branches of those decisions have been executed, it follows that all statements executed under those conditions are also covered. Therefore, achieving 100% decision coverage inherently ensures that every statement in the code has been executed, thus guaranteeing 100% statement coverage.

Understanding this relationship is critical for effective testing, as it allows test designers to prioritize decision coverage knowing that it will also address statement coverage, leading to more thorough testing efforts.