Answer: -
C.Used up rocket stages
Explanation: -
When a rocket goes up, a lot of energy is required to overcome the gravity of the earth.
All rockets use the thrust generated by the rocket propulsion system to overcome the weight of the rocket.
These are from burning of the fuel. Fuels are carried in rocket stages.
Once the initial thrust is over the empty used up rocket stage is discarded to decrease the weight of the rocket.
So, A student watching a simulation of a rocket's flight would notice that the rocket is dropping devices in flight. They are used up rocket stages .
