Which of the following is true of osmosis?

Answer: Option A

Option A: It is a type of diffusion
Osmosis is indeed a special type of diffusion.
Diffusion is the movement of particles from an area of high concentration to an area of low concentration.
Osmosis is specifically the diffusion of water across a semi-permeable membrane.
So, this statement is TRUE.

Option B: Movement is against water's concentration gradient
Osmosis involves water moving from an area of high water concentration to an area of low water concentration.
This means it moves down the concentration gradient, not against it.
So, this statement is FALSE.

Option C: Requires energy
Osmosis is a passive process.
Passive processes don't require the cell to expend any energy (like ATP).
The movement of water is driven by the difference in water concentration.
So, this statement is FALSE.

Option D: All of the above
Since not all the options are true, this statement is FALSE.

Therefore, the correct answer is A: It is a type of diffusion