Question

are more closely related to humans than to fish?
from left to right: a bottlenose dolphin, a human, and atlantic salmon
choose 1 answer:
a dolphins and fish have streamlined bodies for swimming, but humans have a more upright posture for walking on land.
b dolphins and humans have forelimbs with a similar bone structure, but fish do not.
c dolphins and humans have gill slits during embryonic stages of development, and so do fish.

Explanation:

To determine which organisms (dolphins or fish) are more closely related to humans, we analyze the options:

• Option A: Discusses body shapes for movement (streamlined for swimming, upright for walking). This is about adaptation, not evolutionary relatedness.
• Option B: Dolphins (mammals) and humans (mammals) have similar forelimb bone structures (homologous structures), indicating a common ancestor. Fish (non - mammals) lack this structure, supporting a closer relationship between dolphins and humans.
• Option C: Fish have gills throughout life, while dolphins and humans have gill slits only in embryos (a vestigial/developmental trait), but this option incorrectly states fish have the same embryonic gill slit pattern as dolphins and humans in terms of relatedness implication.

Answer:

B. Dolphins and humans have forelimbs with a similar bone structure, but fish do not.