In case of very heavy rain, is the use of the rear fog light mandatory?

In case of very heavy rain, is the use of the rear fog light mandatory?
A)Yes.Correct
B)No, it is optional.
FRONT FOG LIGHT:
- Its installation and use is NOT mandatory.
- It will be white or selective yellow.
- It will be used voluntarily in case of fog, heavy rain, snowfall, smoke or dust clouds, or in similar circumstances.
- It may also be used on narrow roads with many curves, that is, those with a roadway 6.5 m wide or less, signposted with "dangerous curves" signs.
REAR FOG LIGHT:
- Its installation and use is mandatory.
- It will be red.
- It must be used in case of THICK fog, VERY heavy rain, HEAVY snowfall or DENSE clouds of smoke or dust.
The front fog light, during the day, may be on alone with the position lights, but it may also be used together with the dipped or main beam headlights. At night, it will be used at least with the dipped headlights.
The rear fog light, during the day, will be used at least together with the front fog light or the dipped headlights. At night, at least with the dipped headlights.