Answer: C. changes in unit selling prices.
Explanation:
The options given are:
a. the total flexible budget variance
b. the total static budget variance
c. changes in unit selling prices
d. changes in the number of units sold
Based on the information given, the variance can be wholly explained by changes in unit selling prices.
This is due to the fact that the flexible budget revenue variance is calculated and gotten as the difference between the budgeted revenue and the actual revenue at thesame activity level.
Therefore, the number of units will be thesame in both the actual results and the flexble budget. Then, the difference will be as a result of the change in the unit selling price.