Identify the set of correct statement regarding Morgan's experiment on Drosophila.
i. 'X' chromosome of Drosophila male show complete linkage.
ii. The number of linkage groups corresponds to the diploid number of chromosomes.
iii. Drosophila melanogaster has 4 linkage groups.
iv. The term crossing over was coined by Morgan.
v. The phenomenon of crossing over is by and large universal (except in Drosophila)

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.