Biology

The correct answer is: D.amount of fertilizer.

Here’s why:

In an experiment, the independent variable is the one you deliberately change or manipulate to test its effect on the dependent variable. In this case, you are testing how fertilizer affects plant growth, so the amount of fertilizer would be the independent variable, not a constant.

The other factors (amount of sunlight, temperature, and amount of water) are constants. These should be kept the same across all plants in the experiment to ensure that any differences in growth are due to the fertilizer and not other factors.

Let’s break it down:

A.Amount of su...