Manipulating an independent variable involves a. collecting two or more different measurements from participants. b. exposing participants in your study to at least two levels of the independent variable. c. exposing participants in your study to at least one level of the independent variable. d. measuring two or more behaviors and determining whether they are related.

B. exposing participants in your study to at least two levels of the independent variable

Explanation:

The purpose of manipulating and independents or explanatory variable is to have it to systematically change Levels. When this happens various groups of participants will be exposed to different levels of the variable. or it could happen that this same class of participants are exposed to different levels at varying times. An independent sample design is a type of design that has to do with such manipulation.

i think it would be   c)   the raw   materials necesarry to produce   goods

i think im right about 70%