In amplitude modulation

Question

$\begin{array}{1 1}(a)\;\text{amplitude of carrier wave remains constant}\\(b)\; \text{the amplitude of the carrier wave varies accordingly to the frequency of the modulating signal }\\(c)\;\text{the amplitude of the carrier wave varies accordingly to the amplitude of the modulating signal }\\(d)\;\text{Modulating frequency lies in the radio range}\end{array}$