The Focal Lengths of the Objective Lens and the Eyepiece

Multiple Choice

The focal lengths of the objective lens and the eyepiece of a microscope are 0.50 cm and 2.0 cm,respectively,and their separation adjusted for minimum eyestrain is 6.0 cm.If the microscope is focused on a small object,what is the distance between the object and the objective lens?

A) 0.31 cm
B) 0.42 cm
C) 0.49 cm
D) 0.57 cm
E) 0.73 cm