Water in the root enters due to(a)  the function of the root to absorb water(b)  difference in the concentration of ions betweenthe root and the soil(c)  excess water present in the soil(d) diffusion of water in the roots

The process by which water enters the root of a plant is primarily due to (b) the difference in the concentration of ions between the root and the soil. This process is known as osmosis.

Here's a step-by-step explanation:

1. Osmosis is the movement of water from an area of lower solute concentration (in this case, the soil) to an area of higher solute concentration (the root cells), through a semi-permeable membrane (the root cell walls).

2. The root cells have a higher concentration of ions (solutes) compared to the surrounding soil. This creates a concentration gradient.

3. Water in the soil moves towards the root cells to try and balance out this gradient. This is how water enters the root.

4. The function of the root to absorb water (a) is a result of this process, not a cause.

5. Excess water present in the soil (c) can facilitate this process, but it is not the primary reason why water enters the root.

6. Diffusion of water in the roots (d) is a related process that happens after the water has entered the root, as the water continues to move from areas of higher concentration to areas of lower concentration within the plant.