If $$\sigma$$ is the standard deviation of $$x_i(i = 1, 2, ... ... ..., n)$$ then the variation of $$5x_i + 3(i = 1, 2, 3, ... ... ..., n)$$ is

A

$$\sqrt{5}$$

B

$$5 \sigma$$

C

$$5 \sigma^2 + 9$$

D

$$25 \sigma^2$$