The Tucker Company sells three chemicals: petrol, septine, and tridol. Petrol is the companys product with the highest per-unit contribution margin, and tridol has the lowest per-unit contribution margin. Which one of the following events will always result in a decrease in Tuckers overall break-even point?

a.)The installation of a new computer-controlled machine and the subsequent layoff of assembly line workers

b.)A decrease in tridol's selling price

c.)An increase in anticipated sales volume of petrol relative to sales of septine and tridol

d.)	An increase in petrol's raw material cost