Salinization Refers to the Process Where Agricultural Fields Become Unusable

Salinization refers to the process where agricultural fields become unusable because of saline water in the soil root zone. What is the basic reason the water becomes too saline?

A) irrigation water applied to the fields dissolves salt crystals within the soil
B) use of saline water to irrigate crops builds up salts over time
C) plant growth gives off ions, but the salts can't be flushed from the soil
D) ion exchange between rainwater and organic matter in the soil
E) all of the answers listed here