A is the best choice.
Look at the highlighted portion...
In spite of continuing
national trends toward increased consumption of specialty foods, agronomists in the Midwest foresee a gradual reversion to the raising of agricultural staples:
feed corn and hard red wheat
The question here test parallelism.
Inspite of CONTINUING
..... reversion to the RAISING
The other choice, do nto follow this, and some of them alter the meaning. Reversion back, reversion into
are both wrong usage.
Giving another SHOT