The term used for the association of the two genes is:

The correct answer is Option (2) → Linkage

Option (1) Recombination — Incorrect. Recombination is the opposite result: the generation of non-parental gene combinations when linked genes get separated.

Option (2) Linkage — Correct. Morgan used this term for the physical association of two genes on a chromosome; such genes tend to be inherited together.

Option (3) Factors — Incorrect. “Factors” is Mendel's word for genes, the units passed from parents to offspring.

Option (4) Inheritance — Incorrect. Inheritance is the general process by which characters pass from parents to offspring.

NCERT Extract:
Linkage and Recombination – “… Morgan attributed this due to the physical association or linkage of the two genes and coined the term linkage to describe this physical association of genes on a chromosome and the term recombination to describe the generation of non-parental gene combinations (Figure 4.11).”