A student made the electromagnet shown and use it to pick up one sewing pin. Which change to the electromagnet would most likely allow it to pick up two sewing pins?(I attached a picture of the electromagnet and the answer choices)

ANSWER:
C. Double the numer of coils of wire around the nail
STEP-BY-STEP EXPLANATION:
In order to let him pick up two sewing pins, the student must double the number of coils around the nail.