GRE Logical Reading: ETS-GRE逻辑单题ETS - 89FBS36U17LG43W6K$

Ergot is a fungus that can infest the seed heads of any grain crop but is common only on rye. Ergot contains chemicals poisonous to humans. Rye was introduced in Europe in the Middle Ages as a crop for land too poor and damp for wheat to grow well. Thus, rye tended to be the staple of the poorer peasants.