Final answer:
To achieve 100% decision coverage for a single IF statement, two tests are needed: one where the IF condition is true and another where it is false.
Step-by-step explanation:
If you are dealing with a section of code that has one simple IF statement, achieving 100% decision coverage requires conducting two tests. Decision coverage, also known as branch coverage, requires that each possible branch of the decision point be executed at least once. In the case of a single IF statement, there are two branches: one where the condition is true and another where the condition is false. Therefore, one test should be designed to make the IF condition true, and another test should ensure the IF condition is false.