Brings a specimen into good definition when using a microscope

A) arm
B) ocular lens
C) objectives
D) fine-focus dial
E) stage
F) substage
G) shutter or diaphragm
H) oil immersion
I) slide

Fine-Focus Dial

A control knob on a microscope used to make small adjustments in focus to enhance the clarity of the image.

Specimen

A sample of tissue, blood, or other material taken from the body to be tested or analyzed in a laboratory to help diagnose diseases or conditions.

Good Definition

An explanation or description that clearly and accurately conveys the meaning or concept of a term.