A marine biologist dredges up a small animal from the bottom of the ocean. It is uniformly segmented, with short, stiff appendages and soft, flexible skin. It has a complete digestive system and a closed circulatory system, plus multiple true coeloms. Based on this, you determine that the animal must be a(n)
a. mollusc
b. annelid
c. lancelet
d. crustacean
e. roundworm

Annelids in the phylum of animals which includes about 22000 extant species. The animals of this group possess segmented body and thus are called ringed worms.

Each segment of the body contains the same organs and are usually found in the aquatic environment in the hydrothermal vents and the tidal zones. Some species are found in the terrestrial environment.

Since the biologist found the animal from the deep ocean with a segmented body and soft skin therefore, the animal belongs to the annelids.

Thus, option-annelids is the correct answer.