单项选择题

TEXT B
Why do you teach My friend asked the question when I told him that I didn’t want to be considered for an administrative position. He was puzzled that I did not want what was an obvious "step-up" towards what all Americans are taught to want when they grow up: money and power.
Certainly I don’t teach because teaching is easy for me. Teaching is the most difficult of the various ways I have attempted to earn my living: mechanic, writer, carpenter. For me teaching is a red-eye, sweaty-palm, sinking-stomach profession. Red-eye, because I never feel ready to teach no matter how late I stay up preparing. Sweaty-palm, because run always nervous before I enter the classroom, sure that I will be found out for the fool I am. Sinking-stomach, because I leave the classroom an hour later convinced that I was even more boring than usual.
Nor do I teach because I think I know answers, or because I have knowledge I fell compelled to share. Sometimes I am amazed that my students actually take notes on what I say in class!
Why then do I teach
I teach because I like the pace of the academic calendar. June, July and August offer an opportunity for reflection, research, writing.
I teach because teaching is a profession built on change. When the material is the same, I change--and, more importantly, my students change.
I teach because I like the freedom to make my own mistakes, to learn my own lessons, to stimulate myself and my students. As a teacher, I’m my own boss. If I want my freshmen to learn to write by creating their own textbook, who is to say I can’t such course may be huge failures, but we can learn from failures.
I teach because I like to ask questions that students must struggle to answer. The world is full of right answers to bad questions. While teaching, I sometimes find good questions.
I teach because I enjoy finding ways of getting myself and my students out of the ivory tower and into the real world. I once taught a course called "Self-Reliance in a Technological Society". My 15 students read Emerson, Thoreau and Huxley. They kept diaries. They wrote term papers.
But we also set up a corporation, borrowed money, purchased a run-down house and practiced self-reliance by renovating it. At the end of the semester, we sold the house, repaid the loan, paid our taxes and distributed the profits among the group.
So, teaching gives me pace and variety, and challenge, and the opportunity to keep on learning.
From Paragraph 7 we can infer that the writer enjoys freedom to choose ______.