An experimenter studies vision in low light by having participants sit in a darkened room for either

Question:

An experimenter studies vision in low light by having participants sit in a darkened room for either 5, 15, or 25 minutes and then tests their ability to correctly identify 20 objects.
(a) What is the independent variable here?
(b) What are the conditions?
(c) What is the dependent variable?
(d) You would use the scores from which variable to create a frequency distribution?