For the first question about how the author responds to the criticism "stick to basketball," the best answer is:
He points out that his critics weaken their own arguments by associating the value of an opinion with a specific profession.
For the second question regarding which sentence best supports the author’s claim that athletes are sometimes used by governments to make political statements, the best answer is:
“In 1980, the U.S. and 59 other countries boycotted the Summer Olympics in Moscow to protest the Soviet Union’s invasion of Afghanistan.” (paragraph 3)
This sentence provides a clear example of how athletes and sports events have been utilized in political contexts.