Refer to the exhibit.

A company issued its production budget based on an anticipated output of 800 units. Actual output was 1000 units. The details of the costs are shown below:
The budget expenditure variance was:
A company can increase its margin of safety by which of the following independent actions?
(a) Increasing sales and production
(b) Raising the selling price per unit
(c) Raising the variable cost per unit
(d) Lowering fixed costs