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

The correct answer is Option (1) → Torpedo : Torpedoes

Plural of some nouns ending in -o:

Some nouns ending in -o take -es in the plural. Torpedo is one of them. So torpedo → torpedoes. A torpedo is a long bomb that moves under water and hits ships.

Why the Other Options are Incorrect?

Option 2: Stomach : Stomaches — Incorrect. Here -ch sounds like “k”, so the noun takes only -s. Stomach → Stomachs.

Option 3: Monarch : Monarches — Incorrect. This -ch also sounds like “k”. Monarch → Monarchs.

Option 4: Reef : Reef — Incorrect. Reef does not keep the same form in the plural. It takes -s. Reef → Reefs.