Question

scientists have studied the fossilized shells of prehistoric, single-celled marine organisms. some of these shells were thin, which indicates that the organisms lived in very warm ocean water. such evidence indicates that the climate during this time may have been
a moderate
b arctic
c tropical
d the same as it is today

Explanation:

The question states that thin fossilized shells of marine organisms indicate they lived in very warm ocean water. Tropical climates are defined by consistently warm temperatures, which matches the evidence of warm ocean conditions. Moderate climates have milder temperatures, arctic climates are cold, and there is no evidence the climate was identical to today's.

Answer:

C. tropical