A scientist studying the effects of gamma rays on marigolds gathered the data shown below.

Question

Hypothesis: Marigolds exposed to higher levels of radiation will not grow as well as marigolds that are exposed to less radiation

Plant A: Gamma Rays (Rad/day) is 5. Water (mL/week) 50. Sunlight (hours/day) 0. Height (cm) 4.

Plant B: Gamma Rays (Rad/day) is 10. Water (mL/week) 50. Sunlight (hours/day) 2. Height (cm) 7.

Plant C: Gamma Rays (Rad/day) is 15. Water (mL/week) 50. Sunlight (hours/day) 5. Height (cm) 10.

The scientist came to the conclusion that the hypothesis was incorrect. Why is the scientist's conclusion flawed?

A. The scientist's conclusion is flawed because the height of the plants changed and, therefore, the experiment is not controlled.
B. The scientist's conclusion is flawed because the amount of gamma rays changed and, therefore, the experiment is not controlled.
C. The scientist's conclusion is flawed because the number of hours of sunlight changed and, therefore, the experiment is not controlled.
D. The scientist's conclusion is flawed because the amount of water was not changed and, therefore, the experiment is not controlled.

Is the answer D?

Answer 1

No. Don't you see that you are changing BOTH the hours of sunlight AND amount of radiation. Therefore, the height grown could be due to hours of sunlight OR to radiation dose.

Answer 2

Is it c??

Answer 3

not very helpful but is the answer C?