For taillights on motor vehicles, which of the following is true?

For taillights on motor vehicles, the requirement that at least two must be mounted on the rear, one on each side, is in line with safety regulations. This setup ensures that the vehicle is visible from behind, providing necessary signals to other drivers, especially during low-light conditions. The presence of two taillights helps to create a clear visual outline of the vehicle's width and helps prevent accidents.

The other options do not fulfill the standard criteria for taillight regulations. Mounting taillights on the front is not required and could create confusion with other indicators. The specification of blue lights is misleading, as taillights must emit red light, which is standard for visibility and signaling purposes. Additionally, while height regulations exist for some lighting fixtures, the specified range of eight to fifty inches does not accurately reflect taillight mounting height requirements, which generally dictate a specific positioning for optimal visibility rather than offering such a broad range.