The correct options are
A Styrene
B Hexamethylene diamine
C Butadiene
D Caprolactam
Monomers are individual molecules. They make up polymers. So, polymers are large molecules.
Styrene and butadiene are the monomers of Buna-S polymer.
Hexamethylene diamine is used to make nylon-6,6
Caprolactam is used to made nylon-6