I would think A I’m not sure
Answer:
C. Both of the above.........
Answer:
Fine focus.
Explanation:
If you're referencing a microscope, then it would be fine focus. Coarse focus is a basic focus used to properly see a specimen, while fine focus enhance clarity and precision. To use both, you have to gently twist a knob until you can see the specimen at a desired clarity.
Here's a reference image if you need it, it's labeled all the parts of a microscope.
If i'm not mistaken, it's the aorta