The correct answer would be “piernas”
Step-by-step explanation:
Pelos means hairs or strands of hair which, in this case would not make much sense. Cuellos is necks and most people don’t have 2 necks. Narices is noses and the vast majority of people don’t have 2 noses. Piernas means legs and most people do have 2 legs so this would be the most logical answer.