The lowest molecular weight alkene (containing carbon and hydrogen atoms only) capable of exhibiting enantiomerism must have how many carbons?

$\mathrm{A}$ and $\mathrm{B}$ are a pair of what?

The lowest molecular weight alkene which is optically active is/are

(a) $3$-methyl pentene

(b) $2$-methyl pent-$2$-ene

(c) $4$-methyl pentene

(d) $3$-methyl butene

(e) $3$-methyl hex-$2$-ene

Which of the following compounds is optically inactive?