RESEARCH STUDY 3.1 Anderson Is Reading His Morning Paper and Reads the Following

RESEARCH STUDY 3.1
Anderson is reading his morning paper and reads the following headline: "Female Engineering Majors' Effort on Math Problems Depends on Sex of Role Model." (This headline is based on a study conducted by Stout, Dasgupta, Hunsinger, and McManus, 2011.) In the study, female students were asked to complete a math test by either a male math major or a female math major. Female students tried to solve more of the math problems when asked by a female math major compared with a male math major.
-Refer to Research Study 3.1 above to answer the following question. In this study,the authors recorded how many math questions (out of 10 questions) participants tried to solve.This is an example of which of the following?

A) A constant
B) A variable's level
C) A measured variable
D) A manipulated variable
E) None of the above