Answer:
A. Resolution is the correct answer.
Explanation:
Oil immersion is used to increase the numerical aperture and resolution power of the microscope.
Oil such as cedarwood, paraffin oil which has a high refractive index is used and placed between a slipcover and an objective lens that increases the resolving power. This completely immerses the light way among the lens and object observed and allowing more precise features to be observed.
Oil immersion is required for observing unique bacteria and parts of the striations muscle.
