(a) Protonation

(b) Carbonation

(c) Coronation

(d) Catenation

Solution:

Option (d) is the answer.

Catenation is the bonding of atoms of the same element into a series, known as a chain, in chemistry. If the ends of a chain or ring are not linked to each other, it is open; if they are bonded in a ring, it is closed. The terms catenate and catenation come from the Latin word catena, which means “chain.”