Which of one of the following modulated signals are recovered up to a scaling factor using envelope detedtor

Options

A. `20cos200pit+30m(t)cos200pit`
B. `20cos200pit+16m(t)cos200pit`
C. `10m(t)cos400pit`
D. None

Answer

B

Explanation

For option `1 m=(30)/(20)=1.5 mgt1`
for option `2 m=(16)/(20)=0.8 mlt1`
For option `3` signal contains only side bands so message cannot be detected.