According to the classical Indian school of logic, which of the following instruments of knowledge is defined as the knowledge of the relation between a word and its denotation and is produced by the knowledge of resemblance or similarity?

The means defined as grasping the relation between a word and the thing it denotes, arising from perceived resemblance, is comparison.

On hearing that a gavaya resembles a cow, one later meets the animal and knows the word applies to it.

Knowledge of similarity is the ground that fixes the name to the object.

This linking of a term to its denotation through likeness is upamana.

So the pramana in question is comparison, upamana.