Match the items in Column I and Column II.

Column l Column ll
A. SN1 reaction 1. Vic-dibromide
B. Elimination of HX from an alkyl halide 2. Chlorobromocarbons
C. Bromination  of alkenes  3. Racemisation
D. Chemicals in fire extinguisher 4. Saytzeff rule 

Codes:

A B C D
1. 2 3 4 1
2. 3 4 1 2
3. 1 4 3 2
4. 4 1 3 2