The sled with a rough metal bottom would take more force to move over ice, because the rough surface would increase friction and the force needed.
Answer:
The answer is A.
Explanation:
Adaptive immunity recognizes antigens of viruses.
Answer: i would say the independent variable is the soil and the control variable is the seed because it stays the same in all of them to better understand the experiment while the dependent variable is the fertilizer.
Explanation: i am not completely sure but maybe someone else can also answer to verify it first
