JEE Main 2023 Physics question

A scientist is observing a bacteria through a compound microscope. For better analysis and to improve its resolving power he should. (Select the best option)

• (A)Decrease the diameter of the objective lens
• (B)Decrease the focal length of the eye piece
• (C)Increase the refractive index of the medium between the object and objective lensCorrect
• (D)Increase the wavelength of the light