Answer: 0 represents the sea level.
Step-by-step explanation:
Since, for finding the height of any hills of surface of land we used to take the height from the sea level or the surface of sea.
And, when we take distance from a surface we take it at zero.
According to the question,
seagull is 4 feet above the surface of the sea.
That is, when we measure its length from the surface of sea then it is measured to 4 feet.
Thus, for this purpose we did take the level of the surface of sea at zero.
