Final answer:
The animal that uses a muscular foot to bury itself in the sand is the clam (A). Clams possess a muscular foot used for locomotion and anchorage, which is a characteristic feature of many mollusks, allowing them to bury in the sand. The correct option is A. Clam
Step-by-step explanation:
The animal that uses a muscular foot to bury itself in the sand is A. Clam. Clams are part of the phylum Mollusca, which are invertebrates that often possess a hard shell, mantle, and radula.
The functionality of their muscular foot varies among different mollusks, but for clams, the foot assists in locomotion and anchorage within the sand.
In contrast, octopuses (B) belong to the class Cephalopoda and use their foot formed into tentacles and a funnel for locomotion, not for burying in the sand. Sea cucumbers (C) have rows of tube feet for movement but do not use a muscular foot for burying.
Sand dollars (D) are similar to sea urchins and move slowly using rows of tube feet; they do not bury themselves in the sand with a muscular foot.
Mollusks like clams are known for their retractable and extendable foot that can vary in shape and function depending on the species, but in the case of clams, this foot is efficiently used to dig and bury themselves into the sandy seafloor of their aquatic habitats. The correct option is A. Clam