According to the syllabus, decision coverage is a technique that measures the percentage of decision outcomes that have been exercised by a test suite. A decision outcome is the result of evaluating a boolean expression in a control structure, such as an if statement or a switch statement. The goal of decision coverage testing is to cover and validate all the accessible source code by checking and ensuring that each branch of every possible decision point is executed at least once. The answer C is incorrect because it is not a valid use of decision coverage testing. Decision coverage testing does not check that all decisions are based on a numeric value, as there can be other types of values involved in boolean expressions, such as strings or booleans. The other answers are correct because they are valid uses of decision coverage testing. Checking that all decisions have been exercised in a single program or a business process can help to identify defects or missing functionality in the code or process logic. Checking that at least 100% decision coverage has been achieved can help to ensure that all reachable code has been executed and that 100% statement coverage has been achieved as well.

References: Certified Tester Foundation Level Syllabus, Section 4.2.3, page 42-43.