Question

why shouldnt a patient receive an intravenous solution of pure water?
water is hypertonic to blood cells cytosol, which would cause the cells to shrink.
water is hypotonic to blood cells cytosol, so these cells would swell and burst.
water is isotonic to the cytosol of blood cells.

Explanation:

Blood cells' cytosol has solutes. Pure water is hypotonic to it. Osmosis would cause water to move into the cells, making them swell and potentially burst.

Answer:

Water is hypotonic to blood cells' cytosol, so these cells would swell and burst.