Correct choice is (b) Collagen
To explain: Entrapment is a method which involved entrapment of enzyme within suitable gel or fiber. Entrapment can be achieved in 2 ways: Polymerized gel entrapment and microencapsulation. The matrix used for entrapment are agar, collagen, diatomaceous earth, activated carbon, porous ceramic, calcium alginate, K-carr-a-genin etc. Glutaraldehyde is the matrix used for immobilization by covalent binding.