Ben observes that his car will not start. what is a good testable hypothesis?
1.the car will not start.
2. the car is green.
3.the car is out of gasoline.
4.the car has 4 tires.

The correct answer is 3.The car is out of gasoline.

Explanation:

A good testable hypothesis for a car that will not start would be that the car do not contain the fuel to start because any car requires fuel to get started.

So gasoline is a fuel which is also known as petroleum and is widely used as the fuel source for vehicles all over the world. So when any car becomes out of gasoline that car will not start because there will be no energy source to start the engine of the car.  

Therefore the car is out of gasoline is a good testable hypothesis for ben who observed that his car will not start.