Question

Brachiopods and bivalves are both types of organisms that live within shells. Scientists graphed the variety of brachiopod and bivalve fossils that have ever been discovered.

Paleozoic. mesozoic. cenozoic. cambrian. ordevician. silut. devonian. carboniferous. permian. triassic. jurassic. cretaceous. paleog. N plus Q. Genera. Brachiopoda. Bivalvia. Time. M A.

Which statement is best supported by the information in the graph?
A
From 300 ma to 150 ma, the environment for Brachiopoda remained stable
B
From approximately 150 ma to 50 ma, Brachiopoda were in stasis
C
Approximately 375 ma, Brachiopoda developed a mutation that made them a much better fit for their environment
D
Approximately 160 ma, Bivalvia developed a mutation that made them a much better fit for their environment

Answer 1

B

The graph shows little change in brachiopod diversity between about 150 Ma and 50 Ma, which supports the claim of stasis. Choices C and D invoke specific mutations (causal explanations) and A infers environmental stability—neither of which can be directly concluded from the diversity data.