A bacteriophage recognises and attaches to a specific bacterial cell by means of its

Explanation

The tail fibres carry the binding proteins that fit specific receptor molecules on the bacterial cell wall, which is why a phage infects only one species or strain. The head is simply the polyhedral capsid holding the DNA, and the sheath contracts after attachment to drive the core through the wall. Attachment must come first, so a structure involved in penetration cannot be the one that provides recognition.