What would cause a broadcast AM or FM radio to receive an amateur radio transmission unintentionally?

Answer: A. The receiver is unable to reject strong signals outside the AM or FM band

Broadcast AM and FM radios often cannot reject strong signals that are outside their own band. A nearby amateur transmitter can overload the receiver and be heard even though it is on a different frequency. This is a weakness of the receiver, not a fault in the amateur's audio settings.

Tip: Strong nearby signals can overwhelm a cheap receiver.