By default, RouterOS does not pass traffic on a bridge interface through the firewall or queue system. If you want to apply queueing (Simple Queues or other policies) on a bridge interface, you must enable the bridge to use the IP Firewall.
MTCNA Official Course Material - Bridging & IP Firewall Integration:
"If you want to apply queues or firewall rules to traffic flowing through a bridge, you must enable 'use-ip- firewall' under the bridge settings." Rene Meneses MTCNA Guide - Bridge Queuing Section:
"Simple Queues do not affect bridged traffic unless you activate the 'Use IP Firewall' setting in bridge configuration. This pushes the packets through the normal firewall and queueing engine." MikroTik Wiki - Bridge Settings:
"If use-ip-firewall is enabled, then all bridged traffic is also processed by firewall and queues." Options A and C are incorrect because assigning an IP or linking the queue alone does not enforce restrictions at Layer 2.
Option B refers to advanced queueing with mangle + Queue Trees, not Simple Queues.