Which of the following statements are true with reference to Vyapti (concomitance) according to the Nyaya system ?

(a) It expresses the relation between two individual objects only.

(b) It expresses the relation between the classes of individuals.

(c) It can be said to exist between two things if they are related as cause and effect.

(d) It can be said to exist between two things if they are related as species and genus.

Choose the correct answer from the options given below :