Answer:
A. merostomata
Horseshoe crabs are merostomata class
Explanation:
Merostomata is one of the five class of the phylum arthropoda. Horseshoe crabs are not crustaceans. They are the only living representative of a group that flourished successful over 300 million years ago on the earth. They have lived in the coasts of North America and Southeast Asia.
Taxonomy:
PHYLUM: arthropoda
SUBPHYLUM: chelicerata
CLASS: merostomata
ORDERS: xiphosura
FAMILIES: limulidae
