Deduce the identity of the compound from the data provided.

$C_7{H}_{12\text{:}}IR(c_{m-1})$:$33$

A$)1,2-$dimethylcyclopentene

B$)5-$methyl$-2-$hexyne

C$)3,3-$dimethyl$-1-$pentyne

D$)4,4-$dimethyl$-1-$pentyne

Which compound has the lowest carbonyl absorption frequency in an infrared spectrum?

A$)$ ester

B$)$ ketone

C$)$ amide

D$)$ aldehyde

$15-$ Which of the following is the base peak for the compound below?

A$)77$

B$)92$

C$)43$

D$)57$