The species which can best serve as an initiator for the cationic polymerization is

  1. AlCl3
  2. BuLi
  3. LiAlH4
  4. HNO3


Cationic polymerization is a type of chain growth polymerization in which a cationic initiator transfers charge to a monomer which then becomes reactive. Lewis acids can initiate the cationic polymerization.

The correct option is A.