What solution, (hypertonic, hypotonic, isotonic) would make osmosis go faster?

Explanation:

Osmosis is the movement of WATER molecules across a semipermeable membrane (such as the cell membrane) from where there is a high concentration of water to where there is a low concentration of water. The interior of a living cell consists of cytoplasm, which is a solution of mostly water with dissolved substances such as salt.  

Now for the fun stuff!  An Isotonic solution is a solution that has the same concentration of dissolved substances as is found inside the cell.  If a cell is surrounded by isotonic solution, then there is no net movement of water across the membrane by osmosis, because the concentration of water is the same on both sides of the membrane.

A hypertonic solution is a solution with a higher concentration of dissolved substances than is found inside the cell.  If a cell is surrounded by hypertonic solution, then water will move OUT of the cell by osmosis because there is a higher concentration of water inside the cell compared to outside (where there is lots of dissolved salt, etc.)  A cell in hypertonic solution will shrink.  

A hypotonic solution is a solution with a lower concentration of dissolved substances than is found inside the cell.  If a cell is surrounded by hypotonic solution, then water will move INTO the cell by osmosis because there is a higher concentration of water outside the cell compared to inside.  A cell in hypotonic solution will swell up and, if there is no cell wall, may burst.  A silly but simple way to remember that water moves into a cell in hypotonic solution is that "hypo causes the cell to swell up like a hippo"

any abiotic or biotic factor in an ecosystem that causes a population's size to slow or decrease is a limiting factor.

not only is it colder, it also becomes darker, less salty, and more dense.