List I gives the four valid means of knowledge as given by Gautama, and List II gives their description. Match List I with List II:

Perception matches non-erroneous cognition from sense-object contact, inference the cognition presupposing another cognition, comparison the word-denotation relation, and verbal testimony the trustworthy person's statement.

Pratyaksha (perception) arises directly from the senses meeting their objects, so it takes the sense-contact description.

Anumana (inference) always rests on a prior cognition of the pervasion, hence it presupposes some other cognition.

Upamana (comparison) yields knowledge of the tie between a word and the thing it denotes.

Shabda (verbal testimony) is the meaningful statement of a reliable person, understood through its sense.

These are Gautama's four pramanas, the valid means of knowledge in the Nyaya system.