Which of the following statements best describes the rate of air travel in the United States in 2001 (the year of the 9/11 attacks)? Question 10 options: a) U.S. air travel had been steadily increasing for the 10 years prior to 2001, and it continued to rise in 2001. b) U.S. air travel had been steadily increasing for the 10 years prior to 2001, but the rate dropped in 2001. c) U.S. air travel had been steadily decreasing for the 10 years prior to 2001, and it continued to fall in 2001. d) U.S. air travel had been steadily decreasing for the 10 years prior to 2001, but the rate rose in 2001