Question

An audio message signal is a piece of information, which at a particular time,

(1) has only single value

(2) can have two values

(3) can have a single value, or two values, depending on the time instant

(4) must have multiple values

Answer 1

(1) has only single value

Audio signal, at a particular time, have only a single value, as their variation with time, is (usually) basically of the form shown here.