When driving in very heavy rain, is it correct to switch on the rear fog light?

A)No, it can only be used in dense fog or heavy snowfall.
B)Yes, but its use is optional.
C)Yes.Correct
FRONT FOG LIGHT:
- Its installation and use is NOT mandatory.
- It shall be white or selective yellow in colour.
- It shall be used, voluntarily, in the case of fog, heavy rain, snowfall, clouds of smoke or dust, or in circumstances similar to the above.
- It may also be used on narrow roads with many bends, that is, those with a carriageway of 6.5 m wide or less, signposted with "dangerous bends" signs.
REAR FOG LIGHT:
- Its installation and use is mandatory.
- It shall be red in colour.
- It shall be used, mandatorily, in the case of THICK fog, VERY heavy rain, HEAVY snowfall, or DENSE clouds of smoke or dust.
The front fog lights, during the day, may be switched on with only the position lights, but may also be used together with the dipped or full beam lights. At night, they shall be used at minimum with the dipped beam lights.
The rear fog lights, during the day, shall be used at minimum together with the front fog lights or the dipped beam lights. At night, at minimum with the dipped beam lights.