You have an amplifier that is operating with a certain anode voltage, power output, and tank circuit Q. If you decide to increase the anode voltage, but keep want to keep the tank Q and power output the same, how would the value of the tune cap (C2) need to change?
(Note that this is just a hypothetical situation; who in their right mind would increase anode voltage and keep the output power the same?)

C2 needs more capacitance

C2 needs less capacitance

C2 stays the same, the load cap, C3, sets the output power

Answer: C2 needs less capacitance