Identify the Independent Variables and Levels of the IV in Each

Multiple Choice

Identify the independent variables and levels of the IV in each of the following hypotheses:

A) Absence makes the heart grow fonder.
IV: absence (separation for 1 day and no separation)
B) It takes longer to recognize a person in a photograph seen upside down.
IV: photograph position (right-side up and upside down)
C) People feel sadder in blue rooms than pink rooms.
IV: room color (blue room and pink room)
D) Waiting with others reduces anxiety.
IV: affiliation (waiting with others and waiting alone)