When driving in very heavy rain, is it mandatory to use the rear fog lights?

When driving in very heavy rain, is it mandatory to use the rear fog lights?
A)No, it is only optional.
B)Yes.Correct
C)Yes, and the front fog light will also be mandatory.
REAR FOG LIGHT:
- Its installation and use are mandatory.
- It will be red.
- It must be used, mandatorily, in case of THICK fog, VERY heavy rain, HEAVY snowfall or DENSE clouds of smoke or dust.

The use of the front fog light will not be mandatory in any case, it will always be optional.