GRE Logical Reading: ETS-GRE逻辑单题ETS - I6ET9Z6L2EVZTFTTJ$

In a year in which corn is not planted, which of the following is true? A. Either alfalfa or soybeans, but not both, must be planted. B. Either barley or rye, or both, must be planted. C. Both alfalfa and soybeans must be planted. D. Both alfalfa and rye must be planted. E. Either barley or soybeans must be the only crop planted.