In the United States,the Period from 1960 to 2015 Illustrates

In the United States,the period from 1960 to 2015 illustrates that

A) both the number of IPO offerings and the amount of underpricing vary significantly over time.
B) the number of IPO offerings is relatively constant over time but the amount of underpricing varies considerably.
C) both the number of IPO offerings and the amount of underpricing follow a set pattern.
D) IPO underpricing is relatively constant over time but the number of offerings varies quite dramatically.
E) the level of underpricing steadily increased over the period while the number of offerings consistently decreased.