Which of the Following Statements Is Correct

Which of the following statements is correct?

A) In an experimental study, a dependent variable must be categorical, and an independent variable must be continuous.
B) In an experimental study, an independent variable must be ordinal, and a dependent variable must be ratio data.
C) In an experimental study, an independent variable must be categorical, and a dependent variable must be continuous.
D) In an experimental study, an independent variable must be interval data, and a dependent variable must be continuous.