Which one of the following forms propane nitrile as the major product?

What is the major product of the following reaction?
$1\text{-methylcyclopentene} \xrightarrow[\text{Peroxide}]{\text{HBr}} ?$

The rate of $\beta$-dehydrohalogenation in the following halides under treatment with a strong base follows the order:

$1,2-\text{dichloroethane} + NaSCH_2CH_2SNa \to C_4H_8S_2 + (P)$
Unknown product $(P)$ of the above reaction is

The decreasing order of reactivity towards dehydrohalogenation $(E_1)$ reaction of the following compounds is:
$(A)$ $CH_3CH_2CH_2CH_2Cl$
$(B)$ $CH_2=CHCH_2CH_2Cl$
$(C)$ $CH_3CH_2CHClCH_3$
$(D)$ $CH_2=CHCHClCH_3$

The major product obtained in the following conversion is