Question

a scientist is trying to determine the relationship between clams, snails, and squid. when she generates a molecular clock, she is surprised to see that clams and squid are more closely related than clams and snails. which did the molecular clock data show?
clams and squid have been evolving separately for a shorter time than clams and snails.
clams and snails are more similar in related structures than clams and squids.
clams and snails have more in common genetically than clams and squid.
clams and squid have been evolving separately for a longer time than clams and snails.

Explanation:

A molecular clock uses genetic differences to estimate time since species diverged. Closely related species (more recent common ancestor) have evolved separately for a shorter time. Since clams and squid are more closely related than clams and snails, they've evolved separately for a shorter time than clams and snails. Other options: B and C suggest clams - snails are more related (opposite of data), D says longer time (wrong as closer relation means shorter separate evolution).

Answer:

A. Clams and squid have been evolving separately for a shorter time than clams and snails.