Question

a variable whose levels are controlled by the experimenter is called a ________.
a variable whose levels are controlled by the experimenter is called a response variable
options: factor, block, control, response variable.

Explanation:

In experimental design (a concept in Statistics, which is a subfield of Mathematics), a factor is a variable whose levels are controlled by the experimenter. A block is used for grouping experimental units, a control is a standard for comparison, and a response variable is the outcome measured. So the correct term is factor.

Answer:

A. factor