When the sun burns fiercely, （）carbon-14 is produced.

A. About 200,000 people in the world have tried bungee jumping.
B. In order to keep one safe, a rope is tied to the feet of the jumper.
C. Diving into the sea from the top of the cliffs is much more dangerous than bungee jumping.
D. Many people nowadays feel life dull because they haven’t tried bungee jumping.

A. the bad weather
B. the depth of the ocean
C. scientist’ lack of interest
D. unkown