The test variable (independent variable) in Omar's experiment is the masses of the model rockets; option D.
Variables in an experiment refer to those measurements or factors that are under the control of the researcher and which can be altered by the researcher in order to study the effect of changes on the study.
The three types of variables in a study are:
In the study conducted by Omar, the test variable (independent variable) is the time of rocket stays up in the air.
Learn more about variables at: https://brainly.com/question/25223322
#SPJ1