Salinization increases the concentration of in soil.
a. plants
b. nutrients
c. salt
d. water

The correct answer for the blank is - c. salt.

Salinization can be described as a process of increasing salt content in any body (such as water body, soil).

Soil Salinization thus increases the concentration of salt in the soil (in the form of water soluble salt).

Thus, option C) is the right answer.