Final answer:
The answer is 'c) Hermetic,' relating to ancient texts preserving secret knowledge attributed to Hermes Trismegistus and the notion of an airtight seal.
Step-by-step explanation:
The term that refers to ancient books of secrets or to an airtight seal discovered among those secrets, and is derived from the name of a god is c) Hermetic. The Hermetic tradition is connected to Hermes Trismegistus, a syncretic combination of the Greek god Hermes and the Egyptian god Thoth.
This tradition contends that it conceals knowledge, including esoteric wisdom shared through writings such as the Hermetica. The word 'Hermetic' also relates to creating an airtight seal, one of the secrets alleged to have been preserved in these sacred texts, which eventually led to the term 'hermetic' being used in various scientific and alchemical contexts.