Answer:
C. 70
Explanation:
In the expansion of (a + b)^n, the k-th term is ...
nCk·a^(n-k)b^k . . . . . k = 0 to n; nCk = n!/(k!(n-k)!)
Here, we have n=8, k=4, so the term of interest is ...
8C4·x^4y^4 = (8·7·6·5)/(4·3·2·1)x^4y^4 = 70x^4y^4
The coefficient of the term is 70.