B
Below is a question with multiple-choice answers. Choose the correct option based on your reasoning.

### Question:
When stratospheric ozone levels are reduced, the amount of ultraviolet radiation hitting Earth increases. Ozone depletion is most often caused

### Choices:
A. by the reversal of the magnetic field of Earth.
B. when fluorocarbons are released into the atmosphere.
C. when electromagnetic waves from the Sun increase.
D. by abrupt changes in weather and climate patterns.

### Answer:
