If $$Z_1, Z_2, ..., Z_n$$ are $$n$$ independent standard normal variates, then $$\sum_{i=1}^n Z^2_i$$ will follow:

A

chi-squared distribution with degree of freedom 2n

B

F distribution with degree of freedom (n, n)

C

chi-squared distribution with degree of freedom n

D

t distribution with degree of freedom n