Why Do Financial Analysts Prepare Common Size Financial Statements

Why do financial analysts prepare common size financial statements?

A) it is easier to work with financial statements when they are all in the same format
B) they help the analyst identify changes over time in the proportion that each item of expense bears to the entity's total expenses
C) they are a necessary first step in allowing the analyst to develop per capita information
D) they show the dollar amount of change from one year to another for each item of expense,both for the entity studied and the reference group.