The correct option is A (A)-3, (B)-1, (C)-2
All the primary alkyl halides give E2-mechanism easily
So, CH3CH2CH2Br will show E2-mechanism
Tertiary alcohols give E1-mechanism because carbocation so formed is the most stable.
So, B will show E1-mechanism.
Strong EWG at the β carbon and poor leaving group favors the E1cb reaction.
CF3CHCl2 has Fluorine at the β carbon thus it will shows E1cB mechanism.