Answer: the crab will evolve to have more powerful claws.
Explanation: Evolution is the change in the characteristics and features of a species over generation which develops due to natural selection and adaptation within the course of time. The predator is an organism which kills other organism to obtain it as food. The prey is an organism which is killed by the other organism.
According to the given situation, if the prey develops special adaptations to prevent itself from the predator. The predator will also be evolved so as to obtain prey as food. Therefore, the crab will evolve to have more powerful claws is the correct option.