Which of the following is classified as an "Auto" under insurance definitions?

The classification of "Auto" in insurance contexts typically refers to vehicles that are primarily designed for personal transportation. Private passenger motor vehicles, which include cars, vans, and SUVs used by individuals or families for personal use, fit this description perfectly. These vehicles are characterized by their design for the general public's daily commuting, recreational driving, and other personal use, making them a standard category in auto insurance policies.

In contrast, trucks used for commercial transport do not fall under the traditional personal auto category as they are primarily utilized for business purposes. Similarly, heavy construction equipment is specialized machinery not intended for regular road use, and public transportation buses serve a different function entirely as they are designed for transporting passengers on a larger scale, often on fixed routes. Thus, private passenger motor vehicles are distinctly aligned with the typical understanding of an "Auto" in insurance classifications, making this the correct answer.