When are decals allowed on the front windshield?

The correct choice is that decals are allowed on the front windshield if approved by the chief of police. This is important because regulations concerning the placement of decals on windshields are primarily focused on ensuring that the driver's line of sight remains unobstructed to maintain safety. Approval by a designated authority, like the chief of police, is necessary to ensure that any decals placed on the front windshield comply with safety regulations and standards.

Regarding the other choices, while it’s true that decals should not obstruct the driver's view, this guideline alone doesn’t establish a basis for allowing decals. Size restrictions, such as decals being smaller than 2 inches, may also be relevant in other contexts, but they are not sufficient on their own to permit decals on the windshield without the proper approval. Additionally, limiting the allowance of decals strictly to military-related ones does not cover other potential exceptions that may be permitted with authorization. Thus, the overarching requirement for approval ensures compliance with safety regulations.