Efficiency Ratio =

A. $$\frac{{{\text{Number of actual working days in a period}}}}{{{\text{Number of working days in the budget period}}}} \times 100$$

B. $$\frac{{{\text{Actual hours worked}}}}{{{\text{Budgeted hours}}}} \times 100$$

C. $$\frac{{{\text{Standard hours for actual production}}}}{{{\text{Actual hours worked}}}} \times 100$$

D. $$\frac{{{\text{Standard hours for actual production}}}}{{{\text{Budgeted standard hours}}}} \times 100$$

Answer: Option C