Necessary and Sufficeint Conditinos: If A, then B
Necessary Condition
A condition is necessary for B if B cannot be true unless A is true. In other words, if B is true, then A must also be true. This means that A is a prerequisite for B.
For example, if you need to pass a test (B), then you must study (A). If you do not study, you cannot pass the test. Therefore, studying is a necessary condition for passing the test.