If A → B and B → C, which statement is a valid deduction?

• A. A → C
• B. C → A
• C. B → A
• D. A and B

Answer: (A)

Transitivity of implication is being tested. If A implies B and B implies C, then A implies C follows: when A is true, B must be true, and when B is true, C must be true, so C is true whenever A is true. That makes A → C the valid deduction.

The other possibilities don’t follow from the given chain. Knowing C is true doesn’t guarantee A, because the implications only go forward from A to B to C. Similarly, B → A isn’t guaranteed because the information goes in the opposite direction. And A ∧ B isn’t a conclusion you can draw just from A → B and B → C, since A isn’t asserted to be true on its own.