Which of the following refers to the unlawful taking of a car, motorcycle, or boat?

The term that refers to the unlawful taking of a car, motorcycle, or boat is commonly understood to be "stolen car/motorcycle/boat." This phrase directly describes the act of theft where a vehicle is taken without the owner's permission, clearly indicating its status as stolen property. It conveys the precise action of illegally acquiring these modes of transportation.

While "grand theft" also pertains to the theft of items of significant value, and it can include vehicles, the term itself is broader and encompasses various forms of theft beyond just vehicles. It is a classification of theft based on the value of the item, but it does not specify the item taken as clearly as the phrase that directly identifies the vehicles in question.

Additionally, "hit and run felony" refers to a different type of crime involving leaving the scene of an accident without providing contact information or rendering aid, which does not relate to the outright theft of a vehicle. Similarly, "concealing stolen property" involves possession or hiding of items known to be stolen, rather than the initial act of theft itself.

Therefore, the most precise and straightforward answer that directly addresses the unlawful taking of a car, motorcycle, or boat is the term specifically mentioning them as stolen.