Trevor wanted to find out what fertilizer worked best for growing marigolds. He put Miracle Grow on one, Scotts fertilizer on another, and no fertilizer on the third marigold. What is the control? a. Marigold with no fertilizer
b. Type of fertilizer
c. Plant growth
d. Amount of water

a. Marigold with no fertilizer

Explanation:

An experiment contains variables including independent and dependent variables. The independent variable is the variable that is changed by the experimenter, which is the TYPE OF FERTILIZER in this case, while the dependent variable is the measured variable, which is the GROWTH OF MARIGOLDS in this experiment.

However, a control group is a group that does not receive any experimental treatment. In other words, the independent variable is unchanged in the control group. The control group is regarded as the "normal" used to compare with the experimental group (group that receives treatment). In this experiment, the group of marigolds that DOES NOT RECEIVE FERTILIZER is the control group.