(1) Do you enjoy being out in the fresh air? (2) Does nature restore your spirits? (3) You might want to consider hiking as a hobby. (4) It's a hobby you can begin with very little expense. (5) All you need to start is a good pair of hiking shoes.
The first sentence in the paragraph helps to _______ the main idea of the paragraph.
A. delay
B. specify
C. introduce
D. explain