A pintle hook is:
Correct. The pintle hook is the strong rear-mounted hitch that grips the dolly's lunette eye, allowing one trailer to tow another behind it.
CDL Practice Question #349
Category: Doubles/Triples
Why this question matters
This question is one of 50 in our Doubles/Triples bank. The reasoning above comes directly from the AAMVA CDL Manual, the source document used by every U.S. state DMV. Memorizing the underlying rule — not just the letter answer — is what separates passing on the first attempt from a return trip and another fee.