Use the Following Information for Questions

Multiple Choice

Use the following information for questions:
A researcher asked random samples of 50 kindergarten teachers and 50 12th grade teachers how much of their own money they spent on school supplies in the previous school year. They wanted to see if teachers at one grade level spend more than teachers at the other grade level.
-In this study, the grade level taught (kindergarten or 12th grade) is an example of

A) a randomly assigned treatment.
B) an explanatory variable.
C) a response variable.
D) a normal variable.