Final answer:
The fluid near letter D is hypoosmotic compared to the fluid near letter A, meaning it has a lower concentration of solutes and will cause water to move towards the A region.
Step-by-step explanation:
Compared to the fluid near letter A, the fluid near letter D is hypoosmotic compared to A. This means that the fluid in area D has a lower concentration of solutes compared to the fluid in area A. Consequently, water will tend to move from the hypoosmotic D region into the hyperosmotic A region, following osmosis principles, where water moves from an area of lower solute concentration to an area of higher solute concentration across a semipermeable membrane.
It's important to understand that tonicity refers to the ability of an extracellular solution to cause water to move into or out of a cell via osmosis based on the solute concentration differences. Solutions are classified as hypotonic, isotonic, or hypertonic, with hypotonic solutions having lower osmolarity than the cell, isotonic solutions having the same osmolarity as the cell, and hypertonic solutions having a higher osmolarity than the cell.