Question

to test whether a plant grows better in acidic or basic soil, the amount of water and sunlight the plants receive must be controlled as factors called
dependent variables.
observations.
independent variables.
constants.

Explanation:

In an experiment, constants are factors that are kept the same to ensure a fair test. Here, water and sunlight are controlled (kept constant) to test the effect of soil pH (acidic/basic) on plant growth. Dependent variables depend on the independent variable, independent variables are manipulated, and observations are what’s recorded. So the correct term for controlled factors here is constants.

Answer:

D. constants