Which of the following statements is TRUE concerning operating leverage?

a.	The greater the degree of operating leverage, the more that changes in fixed costs will affect variable costs.
b.	Firms with higher degrees of operating leverage are less risky than firms with lower degrees of operating leverage.
c.	Firms with lower degrees of operating leverage have a high level of fixed costs in their cost structure.
d.	The greater the degree of operating leverage, the more that changes in sales activity will affect profits.