Solve the Problem $\mathrm { f } ( \mathrm { x } ) = 6.3 \cos \left( \frac { \pi } { 6 } ( \mathrm { x } - 2 ) \right) + 12.0$

Solve the problem.
-The number of hours of darkness in a coastal town can be modeled by $\mathrm { f } ( \mathrm { x } ) = 6.3 \cos \left( \frac { \pi } { 6 } ( \mathrm { x } - 2 ) \right) + 12.0$ , where $x$ is the month and $x = 1$ corresponds to January. Approximate the number of hours of darkness in April, to the nearest tenth of an hour.

A) $15.2$ hours
B) $22.9$ hours
C) $17.5$ hours
D) 18.3 hours