Time = (distance) / (speed)
If the car really truly covers the entire trip, end to end, at an average speed of 55 miles per hour, then the trip will take
Time = (650 mi) / (55 mi/hr)
Time = (650/55) hours
Time = 11.818 hours which is not one of the choices.
But . . . . .
If 55 miles per hour is the moving speed of the car, then you have to allow a lot more than 11.818 hours for the trip.
-- No car can go 650 miles on one tank of gas. You'll need to take some time to stop for gas.
-- No driver can drive for 11.818 hours straight without stopping. You'll need to take some time to stop and overhaul the driver ... either give him some rest, or else let somebody else take over.
-- Nobody is going to be too happy about going 11.818 hours straight without something to eat and drink.. You'll need to take some time to stop, eat, and drink.
. . . which naturally leads to ==>
-- Nobody can keep going for 11.818 hours straight without a pit stop. You'll need to take some time to stop along the way at a convenient pit. If you fail to plan for it in advance, then the pit you end up stopping at may not actually be a convenient one, but you'll stop and take some time anyway.
The original question was: "How much time should be allowed . . . ?" .
In my 'umble opinion, and based on some experience, my personal advice would be: a MINIMUM of 13 hours, and even THAT's really stepping on it !