A vehicle may be searched based on probable cause without a search warrant if it is mobile and what?

A vehicle may be searched based on probable cause without a search warrant primarily because it is considered an exception to the general rule requiring a warrant for searches. When there are reasonable grounds to believe that the vehicle contains contraband or evidence of a crime, law enforcement officers can perform a search without a warrant.

In this context, probable cause means that there are sufficient facts or evidence that would lead a reasonable officer to believe that contraband related to a crime is present in the vehicle. The mobile nature of vehicles plays a significant role in this exception; they can quickly depart, making it impractical to obtain a warrant in time to preserve evidence.

The other options provided do not establish a standard that supports immediate probable cause needed for a lawful search. Factors such as the driver's age, the vehicle's previous stops, or visible defects do not inherently indicate that contraband is present nor provide the necessary justification for a search without a warrant.