To solve this question simply find the common denominator or the same number for the denominator for all 3 fractions by multiplying both the top and bottom number for the fractions that do not have the largest bottom number which is 12.
1/2 = 6/12 is you multiply the top and bottom by 6
3/4 = 9/12 is you multiply the top and bottom by 3
6/12 + 9/12 + 3/12 = 18/12 = 1 6/12 = 1 1/2.
The correct answer is C.