B is the answer
Explanation: look at the graph
If you don't ventilate your boat after fueling, the gas fumes will stay in the bottom of boat and this is very dangerous.
Explosion can happen if you don't ventilate your boat after fueling so to avoid any explosion or any problem, you have to follow the proper procedure for fueling the boat.
So always ventilate your boat after fueling.
Gravity!! It also keeps the planets in orbit!
-- The wave moves slower through the air than it moved through the water.
-- That causes the wavelength to be shorter than it was in water.
Through a family bloodline