If $$ \sigma$$ is the standard deviation of the observatins $$x_{1}, x_{2}, ... , X_{n}$$, then the standard deviation of $$12x_{1} + 13, 12x_{2} + 13, ..... 12x_{n} + 13$$ is

A

12 $$ \sigma$$

B

$$ \sigma - 13$$

C

$$ \sigma + 13$$

D

$$ \sigma$$