The Use of the "Common" Logarithm in Stock Data Graph

The use of the "common" logarithm in stock data graph is done to

A) confuse the issue.
B) show the up and down swings in the early years because without it, it just looks like an upward sloping line.
C) show the up and down swings in the later years because without it, it just looks like an upward sloping line.
D) show the up and down swings in the middle years because without it, it just looks like an upward sloping line.