Which vehicle is built on a permanent chassis and designed to be used as a dwelling?

The vehicle that is built on a permanent chassis and designed to be used as a dwelling is a house trailer. A house trailer, also known as a mobile home or manufactured home, is specifically constructed for living purposes and is designed to be transported. These vehicles are typically equipped with amenities such as kitchen facilities, bathrooms, and living spaces, making them suitable for residential use.

In contrast, traditional motor vehicles are primarily designed for transportation rather than as living spaces. Buses are intended for public transport and do not typically contain the amenities necessary for habitation. Motorcycles are also focused on transport and lack the structural capacity or design for dwelling purposes. Therefore, among the choices provided, a house trailer is uniquely identified as a vehicle meant for living and meets the criteria described in the question.