In one study described in the textbook (Bursztyn & Jensen, 2014), high school students taking a combination of honors and nonhonors classes were offered an opportunity to sign up for a free SAT preparation course. The students were told either that no one would learn of their decision to sign up or that only the students in the room would learn of their decision. The opportunity was offered either when the students were in one of their honors classes or in one of their nonhonors classes. The proportion of students who signed up for the SAT course was a(n) variable in this study.

The proportion of students who signed up for the SAT course was an Independent variable in this study.

Explanation:

The proportion of students who signed up for the SAT course was an dependent  variable in this study while the opportunity was offered either when the students were in one of their honors classes is the Independent variable.

The two main variables in an experiment are the independent and dependent variable. An independent variable is the variable that is changed or controlled in a scientific experiment to test the effects on the dependent variable. A dependent variable is the variable being tested and measured in a scientific experiment.

answer; i believe the correct answer is prefrontal cortex;

i’m   sure probably just geuss and see which one you can get right, i’m pretty sure it is the combination of goods and services