If there is no dense fog, in what other circumstance can you use the front fog light?

If there is no dense fog, in what other circumstance can you use the front fog light?
A)On narrow stretches of road, with a signposted succession of dangerous curves.Correct
B)In any circumstance in which visibility decreases.
C)You can only switch on the front fog light in dense fog.
FRONT FOG LIGHT:
- Its installation and use is NOT mandatory.
- It will be white or selective yellow.
- It will be used voluntarily in the case of fog, heavy rain, snowfall, clouds of smoke or dust or in similar circumstances.
- It can also be used on narrow roads with many curves, that is, those that, having a carriageway of 6.5 m wide or less, are signposted with «dangerous curves» signs.