According to maximum normal stress theory, the maximum normal stress in the shaft is

A. $$\frac{1}{2}\sqrt {{\sigma ^2} \times 4{\tau ^2}} $$

B. $$\sqrt {{\sigma ^2} \times 4{\tau ^2}} $$

C. $$\frac{1}{2}\left( {\sigma + \sqrt {{\sigma ^2} \times 4{\tau ^2}} } \right)$$

D. $$\sigma + \sqrt {{\sigma ^2} \times 4{\tau ^2}} $$

Answer: Option C