A state agency has contacted you to do a scientific assessment of kudzu in a nature preserve in southern Georgia. They are concerned about the effects of kudzu (the non-native invasive vine) on a small rare plant that grows on the forest floor in the preserve, but which is found nowhere else in the state.

Kudzu is only growing in the east side of the preserve because it hasn't yet had time to invade further. In order to assess the effects of kudzu on the rare plant, you set up the following experiment:

Site 1. On the east side of the park with the kudzu, you set up ten 1m x 1m plots on the forest floor. In each plot you count the number of individuals of the rare plant.

Site 2. On the west side of the park without the kudzu, you set up ten 1m x 1m plots of the forest floor. In each plot you count the number of individuals of the rare plant.

In this experiment, Site 2 is your:

a) variable.

b) control.

c) replication.

d) hypothesis.

problem: Which among the choices is the best answer and describe why.