Which statement best describes the relationship indicated by 'A entails B'?

• A. If A is true, B must be true
• B. If B is true, A must be true
• C. A and B are independent
• D. A and B are both false

Answer: (C)

The main idea here is entailment: A entails B means that whenever A is true, B must also be true. It’s a one-way logical connection, expressed as A -> B. This guarantees a necessary consequence from A to B, but it doesn’t say what happens if A is false.

So, if A is true, B cannot be false under entailment. A simple example helps: if A says “the figure is a triangle,” then B says “the figure has three sides.” If A is true, B must be true. This relation is not the same as saying B implies A, and it’s not about A and B simply being independent or about their truth values when both are false.