The function given is,
[tex]y=-1.5\sin (4x-3\Pi)[/tex]The general form of the sine function is,
[tex]y=a\text{ sin}(bx+c)[/tex]Here, a represents the amplitude.
Compare the general form of function with the given function,
The value of amplitude obtained is,
[tex]a=1.5.[/tex]Ignoring the negative sign.
The correct option is D.
