What type of hitch is attached to the vehicle frame?

A receiver hitch is the correct answer because it is specifically designed to be a part of the vehicle's frame, providing a versatile attachment point for towing various types of trailers. The receiver hitch usually features a square tube that can accept different types of hitch accessories, making it crucial for towing application flexibility. It is built to handle significant weight loads, ensuring stability and safety when connected to a trailer.

In contrast, other hitch types serve different functions. A fixed ball mount is a specific type of hitch that provides a permanent connection point in a fixed position, which may not utilize the modular capabilities of a receiver hitch. A bed mount hitch is installed in the truck bed specifically for attaching gooseneck or fifth-wheel trailers and does not connect to the vehicle frame in the same way. The pin box hitch is generally used in fifth-wheel trailers, where the hitch mechanism attaches to the trailer rather than the vehicle frame directly. Thus, the receiver hitch stands out as the key component affixed directly to the vehicle frame, making it the appropriate choice for this question.