阅读下列短文，从每题所给的四个选项(A、B、C和D)中，选出最佳选项，并在答题卡上将该项涂黑。
B
Five years ago, when I taught art at a school in Seattle, I used Tinkertoys as a test at the beginning of a term to find out something about my students. I put a small set of Tinkertoys in front of each student, and said:”Make something out of the Tinkertoys. You have 45 minutes today - and 45minutes each day for the rest of the week.”
A few students hesitated to start. They waited to see the rest of the class would do. Several others checked the instructions and made something according to one of the model plans provided. Another group built something out of their own imaginations.
Once I had a boy who worked experimentally with Tinkertoys in his free time. His constructions filled a shelf in the art classroom and a good part of his bedroom at home. I was delighted at the presence of such a student. Here was an exceptionally creative mind at work. His presence meant that I had an unexpected teaching assistant in class whose creativity would infect(感染) other students.
Encouraging this kind of thinking has a downside. I ran the risk of losing those students who had a different style of thinking. Without fail one would declare, ” But I’m just not creative.”
“Do you dream at night when you’re asleep?”
“Oh, sure.”
“So tell me one of your most interesting dreams.” The student would tell something wildly imaginative. Flying in the sky or in a time machine or growing three heads. “That’s pretty creative. Who does that for you?”
“Nobody. I do it.”
“Really-at night, when you’re asleep?”
“Sure.”
“Try doing it in the daytime, in class, okay?”
What does the underlined word “downside” in Paragraph 4 probably mean?（）
A. Mistake.
B. Drawback.
C. Difficulty.
D. Burden.