Question

you perform an experiment in which you take 16 pots of strawberry plants and give half of them 1 gram of ammonium nitrate (nh₄no₃) per liter of water and the other half receive only water. each group is then split in half again, and exposed to either eight or 16 hours of light each day. you monitor the height of the plants for four weeks. you observe that plants grown in ammonium nitrate and 16 hours of light grow taller than no ammonium nitrate and eight hours of light.

in this experiment, the size of the pot is

an independent variable.

a dependent variable.

a standardized variable.

a placebo.

a control.

Explanation:

A standardized variable is a factor kept constant across all experimental groups to ensure only the tested independent variables affect the dependent variable. In this experiment, pot size is not manipulated (unlike fertilizer or light hours) nor measured as an outcome (unlike plant height); it is held consistent for all 16 pots to avoid confounding results.

Answer:

C. a standardized variable.