Levi decides to examine the effect of fertilizer on the growth of tomato plants. He chooses four plants for his experiment and applies varying amounts of fertilizer to the three of them. He does not apply fertilizer to one plant. Over a 15-day period, the plants receive fertilizer on Days 1, 4, 7, 10, and 13. Levi measures the height of all of his plants with a meter stick on Days 3, 6, 9, 12, and 15. He also makes sure to hold all experimental factors constant except for the fertilizer. Which statement describes what Levi did to prepare the control group in his experiment?

This question is incomplete because the options are missing; here are the options:

Which statement describes what Levi did to prepare the control group in his experiment?

A) Levi held all experimental factors constant except for fertilizer.

B) Levi did not apply any fertilizer to one of his plants.

C) Levi applied different amounts of fertilizer to three of his plants.

D) Levi measured his plants on five separate days.

The answer to this question is B. Levi did not apply any fertilizer to one of his plants.

Explanation:

In an experiment, the control group refers to the subject or subjects, in this case, the plants, that do not receive the treatment or variable tested by the researcher. This implies the control group for Levi is the plant with no fertilizer because this is the only plant that does not receive the treatment or fertilizer. Moreover, this acts as a control group because Levi can use this plant to determine if the growth of the other three plants is positively or negatively affected by the use of the fertilizer.

true                                                                                                       true true true true true true