This is how you find the mean of a number:
To find the mean of a number, you need to add up all the numbers listed (so, 5, -11, 7, 12, -1 and 0) and then divide it by the amount of numbers there are listed. 5 + -11 + 7 + 12 + -1 + 0 equals 12, and since there are 6 numbers you then divide 12 by 6. 12 divided 6 is 2.
So the answer is A. I hope this helped you!
