Question $5(1$ point$)$

When a carbonyl is part of a conjugated me$-$network, the $C=O$ stratch:

a$)$ has a higher frequency than in a non$-$confugated system.

b$)$ has a lower frequency than in a non$-$confugated system.

c$)$ always occurs at $1710c{m}^{-1}.$

d$)$ cannot be distinguished from the C$-$O stretch in a non$-$confugated system.