About Speed signs A: maximum, matrix sign, advisory and zone: which statement is correct?

If a fixed sign shows '100' and the matrix sign above it shows '80', you may still drive 100 as long as the fixed sign has not been removed.
✓ A3 = maximum speed on an electronic signalling sign (matrix sign); A4 = advisory speed (blue rectangular sign).
A 30-zone sign only applies to the street it stands on; every side street needs its own zone sign again.
A matrix sign above the lane is only an indication; the fixed round signs along the road are the only real, binding traffic signs.

Correct answer: A3 = maximum speed on an electronic signalling sign (matrix sign); A4 = advisory speed (blue rectangular sign).

Explanation

A3 = maximum speed on an electronic signalling sign (matrix sign); A4 = advisory speed (blue rectangular sign)

The LOWEST indicated maximum speed applies, not the more permanent one. With sign 100 + matrix 80, 80 applies
A sign with 'zone' above it applies to the ENTIRE indicated area, until the end-of-zone sign — not only to the street the sign stands on
Traffic signs may be displayed on an electronic signalling sign; when a fixed sign and a matrix sign both show a speed at once, the lowest one applies