A farmer is interested in determining the effect of fertilizer use, water use, and natural disaster on his corn yield. He estimates a regression and obtains the following results: yield = 23 + 3.2fertilizer + 2.1water - 6.5storm In the equation, fertilizer is measure in lb/acre, water is measured in gallons/acre, yield is measured in bu/acre, and the variable storm is a dummy variable that takes the value 1 if a storm happens and O if a storm does not happen. What is the effect of a storm on yield? If a storm happens then yield will decrease by 6.5 bu/acre If a storm happens then yield will increase by 6.5 bu/acre O If a storm happens then yield will decrease by 23 + 6.5 = 29.5 bu/acre If a storm happens then yield will decrease by 23 bu/acre If a storm happens then yield will increase by 23 +6.5 = 29.5 bu/acre O If a storm happens then yield will increase by 23 bu/acre