Correct Answer: D
Explanation:
The topic sentence of the first paragraph gives this indication.
Choice (A) is incorrect; discussed in the passage; it is not the entire concept of the selection.
Choice (B) is incorrect; there is no mention of a non-threatening environment.
Choice (C) is incorrect; there is a point that furnishings may be unpleasant when designed for children but used by adolescents, but this is not main idea of the selection.
Choice (E) is incorrect; while this may a true statement, it is not the main idea of this selection.