About The seven categories of traffic signs (appendix 1): which statement is WRONG?

Command signs (round, blue) are a separate category from category C (round, red border).

A yellow diamond-shaped sign belongs to category A (speed).

B1 (priority road) has its own yellow diamond shape, not a triangle.

F1 is listed literally under 'Other commands and prohibitions', not under chapter C 'Closure'.

Explanation

trap: category confused. Category A (speed) consists of round signs (A1, A2...); the yellow diamond shape is unique to category B (priority, sign B1)