What is the risk in shifting gears while driving a heavy vehicle down a steep descent?

1. A There is no risk in shifting gears, and gears are not so important, as long as one of them is operated.
2. B Shifting gears while driving down a steep descent is not dangerous.
3. C There is no danger. By shifting from low gear to high gear while driving on a steep descent, the vehicle can drive faster.
4. D There is a risk that the gear would not shift and the vehicle would stay in neutral gear.