When carbon dioxide is dissolved in the ocean, what can it be turned into? A. Fossil fuels
B. Seashells
C. Nitrates
D. Zooplankton

I think its B. seashells?

Explanation:

Organisms in the ocean take Carbon Dioxide and turn it into carbonate CO 2/3

Carbonate is often combined with ions like CA 2+  and MG 2+

The Calcium Carbonate makes up the hard structures of corals, and sea shells. The amount of Carbon in the Coral reefs far exceeds the amount of Carbon Dioxide dissolved in the oceans.

the food storage products of chrysophytes are oils or the polysaccharide laminarin.   formerly classified as plants, the chrysophytes contain the photosynthetic pigments chlorophyll a and c all but the yellow-green algae also contain the carotenoid pigment fucoxanthin.

stimulus is a change in the environment that causes an organism to react. the response is the reaction to the stimulus. some examples of stimuli for zebras are drought, to many predators, and bad feeding grounds such as dead grass or plants. zebras respond to stimuli just like all other living organisms