How many dangerous sports does the author mention in this passage

A．To compare the old Romans with today's people
B．to give an example
C．to show human beings in the past know nothing better
D．to indicate human beings are used to bloodthirsty

A．vicious and dangerous sports should be banned by law
B．people are willing to pay vast sums money to see violence
C．to compare two different attitudes towards dangerous sports
D．people are bloodthirsty in sports