The correct answer is: $\frac{{{\text{Standard hours for actual production}}}}{{{\text{Budgeted standard hours}}}} \times 100$.
The calendar ratio is a measure of how well a company is able to meet its production goals. It is calculated by dividing the number of standard hours for actual production by the budgeted standard hours. A ratio of 100% indicates that the company met its production goals. A ratio below 100% indicates that the company did not meet its production goals.
Option A is the number of actual working days in a period divided by the number of working days in the budget period. This ratio is not a measure of production efficiency. It is simply a measure of how many days the company was able to work.
Option B is the actual hours worked divided by the budgeted hours. This ratio is a measure of labor efficiency. It indicates how well the company is able to use its labor resources. However, it does not take into account the number of units produced.
Option C is the standard hours for actual production divided by the actual hours worked. This ratio is a measure of labor productivity. It indicates how many units the company is able to produce with each hour of labor. However, it does not take into account the number of units that were budgeted to be produced.
Option D is the standard hours for actual production divided by the budgeted standard hours. This ratio is the only option that takes into account both the number of units produced and the number of units that were budgeted to be produced. It is therefore the best measure of production efficiency.