The MacPherson strut is a widely used front suspension system in modern cars.
It combines the shock absorber and coil spring into a single unit, saving space and weight.
The upper end of this assembly must be fixed firmly to handle loads from the road.
It is mounted on a seat or bracket attached directly to the vehicle’s structural frame or body shell.
This allows the suspension forces to be properly transferred to the chassis.
Side members, axle pads, or cross members do not specifically provide this seat in MacPherson strut design.
Therefore, the correct answer is structural frame.