Answer:
The correct option is;
1. Lighter
The longer any aircraft is in the air, the Lighter it becomes
Step-by-step explanation:
The fuel fraction of an aircraft or the propellant fraction of a spacecraft, is the weight of fuel carried by the aircraft divided by the total wieght of the aircraft including the fuel given by the following relation;
Where:
ζ = Fuel fraction
ΔW = Weight of fuel in aircraft
W₁ = Total weight of aircraft
An airplane fuel fraction is important in determining how far a plane can fly. The fuel fraction can be up to 45% of the total weight of commercial airliners, while long distance airplanes such as a global flyer can attain a fuel fraction of over 80% which is about 5 times the empty weight of the airplane carried on as fuel.
Therefore, the longer the aircraft is in the air, and burning off the fuel loaded, the lighter it becomes.