Solve the Problem $\mathrm { f } ( \mathrm { x } ) = 5 ^ { \mathrm { x } }$

Multiple Choice

Solve the problem.
-If $\mathrm { f } ( \mathrm { x } ) = 5 ^ { \mathrm { x } }$ , find $\mathrm { f } \left( \log _ { 5 } 8 \right)$ .

A) 8
B) 5
C) 40
D) $\log _ { 8 } x$