Answer

A-S; B-P;C-Q;D-R

Explanation

Dehydrohalogenation of 1-chlorobutane-(S) 1-Butene
Dehydration of 1-butanol-(P) trans-2-Butene
Wurtz reaction of isopropyl bromide-(Q) 2,3Dimethylbutane
Decarboxlation of sodium isobutyrate-(R) Propane