Question $12$:

When cyclopropane is treated with HI$,1-$iodopropane is formed. A similar type of reaction does not occur with cyclopentane or cyclohexane. How do you account for the reactivity of cyclopropane?

$($a$)$ The ring strain in cyclopropane increases its reactivity.

$($b$)$ The bond angle in cyclohexane is smaller than the bond angle in cyclopentane.

$($c$)$ The carbon$-$carbon bond lengths are longer in cyclopentane.