What is the product obtained from the dehydration of glycerol?

Octane number can be changed by

Given below are two statements.
Statement $I$: On heating with $KHSO_4$,glycerol is dehydrated and acrolein is formed.
Statement $II$: Acrolein has fruity odour and can be used to test glycerol's presence.
Choose the correct option.

The octane number of diesel is increased by adding ..........

The major product $'A'$ of the following given reaction has $......\,sp^2$ hybridized carbon atoms.
$2,7-\text{Dimethyl}-2,6-\text{octadiene} \xrightarrow{H^{+}} A \text{ (Major Product)}$

The product of the above reaction will be: