The Sixteenth Amendment to the U.S. Constitution gave the federal government the power to levy a national income tax

An experimental research hypothesis

A) Seeks correlational relationships. B) Is a vague statement. C) Is a specific prediction. D) Is a general prediction.

An independent variable cannot be a manipulated variable if it is

a. a task variable. b. an instructional variable. c. a subject variable. d. a qualitative variable