Question

3.4.2 test (cst): computer-scored unit test

number of fish
2500
2000
1500
1000
500
0
0 1 2 3 4 5
year

which statement best explains the data?

a. the fish got sick from eating the algae.
b. the pond was too small for the original fish population.
c. the algae poisoned the pond.
d. the pond experienced an algal bloom.

Explanation:

To determine the best explanation for the fish population decline (from the graph), we analyze each option:

• Option A: No info about algae consumption causing sickness is implied by the graph.
• Option B: The initial population was stable (year 0 - 1), so the pond size not being an issue initially rules this out.
• Option C: No direct indication of algae poisoning from the graph alone.
• Option D: An algal bloom can deplete oxygen in the pond, leading to fish deaths. This aligns with a declining fish population over time, as algal blooms often harm aquatic life by reducing oxygen availability.

Answer:

D. The pond experienced an algal bloom.