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

Louse:Lice

The correct pair of singular and plural is:

☀ Louse:Lice

Explanation for each option:

☀ Horse:Horse: This is incorrect. The plural form of "Horse" is "Horses."

☀ Louse:Lice: This is correct. The singular form of "Louse" is "Louse," and the plural form is "Lice."

☀ Mouse:Mouses: This is incorrect. The correct plural form of "Mouse" is "Mice."

☀ Topaz:Topazs: This is incorrect. The plural form of "Topaz" is "Topazes."