About Under-signs: explanation, restriction, exemption and distance: which statement is WRONG?

If an under-sign at E4 through E8, E12 or E13 shows days or hours, the orders/prohibitions apply ONLY during those days or hours — outside that window the ban does not apply.
'500 m' (no arrows) = applies over 500 metres from here; '↑500 m↑' (with arrows) = applies for the coming 500 metres — two different applications of the same number, not synonyms.
'uitgezonderd' + symbol = the sign does NOT apply to that group (exemption); a bare symbol without 'uitgezonderd' restricts the sign TO that group instead.
✓ An under-sign with a symbol applies on its own, even if the main sign above it has been removed or is illegible.

Correct answer: An under-sign with a symbol applies on its own, even if the main sign above it has been removed or is illegible.

Explanation

An under-sign contains a further explanation OF THE TRAFFIC SIGN; without a main sign an under-sign has no independent effect

If an under-sign at E4 through E8, E12 or E13 shows days or hours, the orders/prohibitions apply ONLY during those days or hours — outside that window the ban does not apply
'500 m' (no arrows) = applies over 500 metres from here; '↑500 m↑' (with arrows) = applies for the coming 500 metres — two different applications of the same number, not synonyms
'uitgezonderd' + symbol = the sign does NOT apply to that group (exemption); a bare symbol without 'uitgezonderd' restricts the sign TO that group instead