The correct option is D.
In the combustion chamber of a gas turbine engine, the fuel oil is mixed with a proper portion of a compressed air, this is then ignited. The major function of the combustion chamber is to add energy to the system to power the turbine.
Period is T=1/f
T=1/60 = 16.67 milliseconds
Please see the solution in the attached drawing.
Read it from the top down.
If you ever come back again, with one that has
an AC source and an L or a C in the circuit, I'll
be looking for more than 5 points for that one. :-)