Which of the following horn conditions would cause it to fail inspection?

A horn is a crucial safety feature of any vehicle, as it serves to alert others on the road and prevent accidents. For a horn to pass inspection, it should be fully operational and safe to use.

The situation where the horn switch interferes with other controls is particularly problematic. This condition could create a scenario where the driver cannot use the horn effectively, which may hinder their ability to alert other drivers, pedestrians, or cyclists of their presence or intentions. Interference with other controls implies that the horn's operation could lead to unintended actions or distractions while driving, compromising overall vehicle safety. Thus, this condition would indeed cause the vehicle to fail the safety inspection.

In contrast, a horn that is loud but inoperative or one that has no sound at all represents failure conditions as well; however, they are straightforward failings. A horn that is loud but does not work, or one that produces no sound, both indicate that the alerting functionality is completely compromised. The option stating that the horn is audible from 200 feet indicates that the horn is functional and meets an acceptable level of sound output, which does not lead to a failure in inspection.