Answer: B. 2
Step-by-step explanation: When you solve for mean, you have to add all the numbers together, then whatever your answer is, then divide it with the number of values.
3 + 1 + 2 + 3 + 1 + 2 + 3 + 1 + 2 + 1 + 3 + 2 = 24
24 divided by 12 = 2
The students spent an average of 2 hours studying.