Step-by-step explanation:
The given equation is as follows.

Reactants are the species present on the left hand side of a chemical equation.
Products are the species present on the right hand side of a chemical equation.
Whereas coefficients are the number present in front of formulas.
Therefore, in the given reaction equation, matched terms are as follows.
- Reactant is

- Product is AB.
- Coefficient is 2.