The correct answer is A. value of stock.
Fire insurance is a type of insurance that protects businesses and individuals from financial losses caused by fire. The value of the stock is the most important factor in determining the cost of fire insurance, as it is the amount of money that would be lost if the stock were to be destroyed in a fire.
The other options are not as important factors in determining the cost of fire insurance. The volume of stock is the amount of space that the stock takes up, but this does not necessarily correlate with the value of the stock. The number of stores requisition is the number of times that stock is ordered, but this does not necessarily correlate with the value of the stock. The material used to make the stock is also not as important a factor as the value of the stock.
Therefore, the correct answer is A. value of stock.