31, 1, 12, 2, 21, 22, 1, 0, 31, 13
Remember, the mode is the number that appears the most! :)
So, let's go through each number and see how many times they appear within this data set :)
31 : appears twice
1 : appears twice
12 : appears once
2: appears once
21 : appears once
22 : once
0 : appears once
13 : appears once
So, 31 and 1 both appear twice, therefore giving us the answer.
C) 1 & 31
~Hope I helped!~