Question

a student hypothesized that pillar coral eat and digest zooxanthellae for energy. which observation would cause the student to change this hypothesis?
a. pillar coral are a type of coral that needs sunlight to survive.
b. zooxanthellae are a type of phytoplankton found in the ocean.
c. the pillar coral are an important part of many coral reefs.
d. the zooxanthellae in a pillar corals body are alive.

Explanation:

If pillar coral ate and digested zooxanthellae for energy, the zooxanthellae would be dead. But if the zooxanthellae in a pillar coral's body are alive (as in option D), it goes against the hypothesis of digestion for energy. Option A about sunlight need doesn't directly refute the digestion - energy hypothesis. Option B just defines zooxanthellae. Option C is about pillar coral's role in reefs, not related to the hypothesis.

Answer:

D. The zooxanthellae in a pillar coral's body are alive.