After Identifying the Factors of the Starting Prefix and Target

After identifying the factors of the starting prefix and target prefix,what is the next step in converting metric system units using Approach 2?

A) Calculate the ratio of the larger factor to the smaller factor.
B) Determine the sum of the larger factor and the smaller factor.
C) Multiply the starting value by 10Δx, where Δx is the difference between the powers of 10.
D) Set up an equation of ratios and subtract the larger ratio from the smaller ratio.