Match the terms is Column-I with their explanation in Column-II:

	Column I		Column II
A.	Polycythemia	I.	Decrease in number of WBCs
B.	Erythrocytopenia	II.	Increase in number of RBCs
C.	Leukemia	III.	Decrease in number of RBCs
D.	Leucopenia	IV.	Uncontrolled increase in number of WBCs

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.