HELP 30 POINTS

The model for long term average temperature f (x), in degree celsius, at the wilburn airport is represented by the equation f(x)=5cos(x/12)+14.5. If x represents the month of the year, in which months will the temperature be 17°C?

A. x=pi/3+24pi(n) and x=5pi/3+24pi(n)
B. x=pi/3+2pi(n) and x= 5pi/3 + 2pi(n)
C. x=4pi + 24 pi(n) and x = 20pi + 24 pi(n)
D. 4pi+2pi(n) and x=20pi +2pi(n)