When nitrogen-rich runoff from farms enters a nearby farm, it causes abundant growth of algal mat on the pond surface. As a result, underwater plants in the pond begin to die. Identify the limiting factor that is most responsible for causing the underwater plants to die.
A B C D
oxygen sunlight nitrogen carbon dioxide
Question: When nitrogen-rich runoff from farms enters a nearby farm, it causes abundant growth of algal mat on the pond surface. As a result, underwater plants in the pond begin to die. Identify the limiting factor that is most responsible for causing the underwater plants to die.
(A) oxygen
(B) sunlight
(C) nitrogen
(D) carbon dioxide

Answer: (B) sunlight
Answer: (A) oxygen
Question: When nitrogen-rich runoff from farms enters a nearby farm, it causes abundant growth of algal mat on the pond surface. As a result, underwater plants in the pond begin to die. Identify the limiting factor that is most responsible for causing the underwater plants to die.
(A) oxygen
(B) sunlight
(C) nitrogen
(D) carbon dioxide
Answer: (B) sunlight