Which of the following is a correct pair of singular and plural?

The correct answer is Option (2) → Analysis : Analyses

Plural of nouns ending in -is:

Nouns ending in -is change -is to -es in the plural. So analysis → analyses. An analysis is a careful study of something.

Why the Other Options are Incorrect?

Option 1: Mouse : Mouses — Incorrect. Mouse has an irregular plural. Mouse → Mice.

Option 3: Diagnosis : Diagnosises — Incorrect. Diagnosis also ends in -is, so it follows the same rule. Diagnosis → Diagnoses.

Option 4: Piano : Pianoes — Incorrect. Piano takes only -s. Piano → Pianos.