Raisins swell in water due to endosmosis, which is actually diffusion.... option A

Imbibition Process in Raisins
Imbibition is the process where substances absorb water and swell due to the entry of water into their structure. When raisins are placed in water, they undergo imbibition, causing them to swell. Let's explore this process in detail:

How Imbibition Works
Imbibition occurs when the water potential of the surrounding medium is lower than that of the substance being imbibed. In the case of raisins, the dried fruit has a lower water potential compared to the water it is placed in. As a result, water molecules move into the raisin through osmosis, causing it to swell.

Swelling of Raisins
As water enters the raisin through imbibition, it diffuses into the dried cells of the fruit. The cellulose walls of the cells absorb the water, causing them to expand and swell. This results in the raisin increasing in size and becoming plump and soft.

Imbibition vs. Diffusion
While diffusion is the movement of molecules from an area of higher concentration to lower concentration, imbibition specifically refers to the absorption of water by solids, especially when the water potential outside is higher. In the case of raisins, imbibition is the process responsible for their swelling when placed in water.
In conclusion, the swelling of raisins placed in water is a result of the imbibition process. As water is absorbed by the dried fruit, it causes the cells to expand and the raisins to swell. This phenomenon highlights the importance of imbibition in biological processes involving the absorption of water by solids.