A histogram shows ranges of the number of T-shirts owned by the number of friends. The horizontal axis shows number of T-shirts ranging from 0 to 15 in increments of 3. The vertical axis ranges from 0 to 5 in increments of 1. The graph shows the following data: 3 to 6 T-shirts owned by 5 friends; 6 to 9 T-shirts owned by 1 friend; 9 to 12 T-shirts owned by 2 friends; 12 to 15 T-shirts owned by 3 friends. D’Marco makes this histogram to show the numbers of T-shirts some of his friends own. How many of these friends own at least 6 but fewer than 9 T-shirts? Put in one correct answer.