Doesn’t normally happen until your 40’s or 50’s
No. Osmosis is the movement of a solvent through a membrane (semi-permeable) from a less concentrated solution to a more concentrated solution to the point where the two sides reach equilibrium. Isotonic solutions are solutions where the two sides of the membrane are already at equilibrium - so there is no movement of the solvent (like water) - so this is different from osmosis.
There are several different processes, including glycolysis and the Calvin Cycle, but the umbrella term for getting energy from glucose is cellular respiration.
I think the answer might be A or B. Not so sure...