Consider the proton NMR spectra of Compounds I, II$,$

and III below in $CDC{l}_3$ solution:

I

II

III

Which of these compounds is$/$are expected to produce an

NMR spectrum that consists exclusively of one singlet$,$

one triplet, and one quartet?

A$)$ I only

B$)$ II only

C$)$ I and III only

D$)$ II and III only