If the objective lenses of a microscope can be changed without losing focus on the specimen, they are said to be . A) equifocal. B) totifocal. C) parfocal. D) optifocal.

C) parfocal.

Explanation:

A microscope can be defined as an optical device that is typically used to make an enlarged (magnified) image of a minute (small) object and as such reveals all the little information about the object that cannot be seen by the natural human eye.

A microscope is said to be parfocal if its lense is binocular and they can both be in focus.

Hence, if the objective lenses of a microscope can be changed without losing focus on the specimen, they are said to be parfocal.