By thE miD-1960s, Cotton FArmErs inCEntrAlAmEriCA FounD thAt pEstiCiDEs
A、wErE wiping out 50% oF thE pEsts plAguing thE Crops.
B．wErE DEstroying 50% oF thE Crops thEy wErE mEAnt to protECt.
C、wErE CAusing A 50% inCrEAsE in thE numBEr oF nEw pEsts rEportED、
D．wErE Costing 50% oF thE totAl Amount thEy spEnt on thEir Crops.