Answer:
Graph D
Step-by-step explanation:
Initially, Marlon was looking for his pump. Thus, no air was pumped into the balloon until he got the pump. On getting the pump, he inflated the balloon with air at a constant rate, after which he tied it with a string to prevent the air from escaping.
The analysis is that, at the time he decided to inflate the balloon till he got a pump, the volume of air in the balloon is zero with respect to time. Pumping air at a steady rate into the balloon increases the volume of air flowing into it gradually and steadily.
When the volume got to a definite amount, he stopped pumping air and tied with a string. Thus, the volume of air in the balloon remains constant.
