Which of the following are experiments? 

1. Researchers ask subjects whether they drink coffee regularly and how much sleep they get per night to see whether there is an association between coffee consumption and amount of sleep. 

2. Researchers randomly assign half the subjects to wear a certain kind of shoe and half the subjects to be barefoot. They then measure how high they all can jump to see whether the shoe helps jumping ability. 

3. Researchers have subjects play a memorization game twice, once while listening to music and once without music. The order in which each does this is randomly determined. They want to see whether there is an association between memorization and the presence of music. 

A. Only 1 is an experiment. 

B. Only 2 is an experiment. 

C. Both 2 and 3 are experiments. 

D. All three are experiments. 

E. None of the above answers is correct.