The components of blood can be separated by spinning them at high speed. Figure I shows a tube of blood that has been separated in this way.
Figure 1
substance X
white blood cells and platelets
red blood cells
- Identify the substance labelled X.

Plasma

Explanation:

We don't have the figure, but I think the answer is probably plasma.

Blood plasma is the fluid that blood cells are suspended in. When blood is spun at high speed, the cells separate away from the plasma into different layers because of their different weights and shapes.

Plasma is liquid portion of blood. It transports nutrients and wastes and maintains  homeostasis.

maritime tropical may be your answer.