You will be given a definition of a task first, then some input of the task.
In this task, you are given a multiple-choice question and you have to pick the correct option. Answer with option indexes (i.e., "A", "B", "C", and "D").

What is an example of humans building houses in a ecosystem and causing change in the environment as a result? (A) a dog house is placed in a fenced in back yard (B) a birdbath is placed in a park with a low squirrel population (C) a city is built over a park and deer lose their home (D) a small house is built in the forest and animals are fed there
Output:
C