Step 1: Check the Assertion. A reflex (for example, pulling the hand away from a hot object) happens in a fraction of a second, so A is true. Step 2: Check the Reason. Reflexes are processed in the spinal cord (for some reflexes, lower brain parts), through a short reflex arc. The cerebrum, which controls thinking and voluntary action, is not needed. So R is false. Step 3: In fact, the speed comes from the short pathway that bypasses the thinking part of the brain. Answer: A is true but R is false.