In Indian logic (Nyaya), anumana (inference) is knowledge gained through a mark or sign (hetu / linga). Its whole validity rests on vyapti — the invariable, universal concomitance between the middle term (the sign or reason, hetu) and the major term (the thing to be proved, sadhya).

Consider the classic example: The hill has fire, because it has smoke. Here smoke is the middle term (hetu) and fire is the major term (sadhya). The inference works only because there is an invariable relation — wherever there is smoke, there is fire — established by vyapti. Once this universal concomitance between the middle and major terms is grasped and the middle term is seen present in the minor term (the hill), the conclusion follows. Hence anumana is rooted in the invariable concomitance between the middle term and the major term.

The option speaking of a variable relation between minor and major terms is wrong because inference is never based on a variable link, and the minor–major connection is the conclusion itself, not its ground. The option pairing the middle and minor terms describes the presence of the reason in the subject (paksadharmata), not the universal relation that licenses the inference. The option calling the concomitance between middle and major terms merely variable is wrong because vyapti must be invariable — a variable relation could not guarantee the conclusion.

Correct answer: invariable concomitance between middle term and major term.