To eliminate the possibility of using an answer more than once on a matching question, one should a. cross out used answers c. both of these b. write the capital form of the letter d. none of these

To eliminate the possibility of using an answer more than once on a matching question, one should preferabbly cross out the answer which has already been used. But that isn’t a hard and fast rule. If you feel comfortable with using any other method that makes you understand better, you can always go for  

it is snorkeling, apex verified.