13. You put fifteen small fish in a small aquarium which contains two gallons of water. You fed
them with right amount of food. After five days, some of the fish died. Why did it happen?

A. The smelly and cloudy water in the aquarium was not replaced.
B. The aquarium did not have enough temperature range.
C. The aquarium was moved to another place.
D. There was no enough space for the number of fish.

14. Man interferes in the balance of nature when?

A. pollutes air and water
B. practice selective logging
C. help control overpopulation
D. disposes his garbage properly

15. Which of the following can help conserve our ecosystem?

A. Construct buildings near river banks.
B. Protects the forests and bodies of water against harmful activities.
C. Improve ecosystem by inviting tourists to visit your place.
D. Encourage the political leaders to build farm to market roads to reach all beautiful places

16. In the picture, what type of interaction is shown?

A. mutualism
C. competition
B. commensalism
D. predation​