Final answer:
The correct answer is Above. When a drop of blood is placed on a slide, a second slide is placed above the first slide to spread and protect the blood sample.
Step-by-step explanation:
The correct answer is a) Above.
When a drop of blood is placed on a slide, a second slide is placed above the first slide. The second slide acts as a cover slip that helps to spread and flatten the blood sample for observation under a microscope. Placing the second slide above the first slide also helps to prevent the blood sample from drying out.
For example, when examining a blood smear to analyze red blood cells or white blood cells, the cover slip is placed above the blood smear on the slide. This ensures that the cells are adequately spread and protected.