Correct one plzz

120. If a message signal of frequency 10 kHz and 11 peak voltage 12 V is used to modulate a carrier wave of frequency 1 MHz, the modulation index is 0.6. To make the modulation index 0.75, the carrier peak voltage should be (a) decreased by 25% (b) increased by 25% (c) decreased by 20% (d) increased by 20%