If a Plant Were Grazed Upon by Individuals of a Snail

If a plant were grazed upon by individuals of a snail population,and the plant produced compounds to deter further feeding,then what might occur?

A) The plant will do nothing different since it is now chemically defended.
B) The plant may experiences a trade-off of some sort, because there is likely a cost to producing the compounds that deter grazers.
C) The plant will not experience any trade-offs since it has evolved with this grazing snail.
D) The snail will likely continue to graze because it is immune to the chemicals this plant produces.