Concept:The Earth’s curved surface hides the lower parts of a distant object first.
Explanation:As a ship sails toward an observer from beyond the horizon, only the topmost part is visible at first.
The mast is the highest part of the ship, so it appears above the horizon first.
The hull is lower and closer to the water, so it remains hidden behind the curvature of the Earth until the ship comes nearer.
Therefore, the correct order of visibility is mast first, then the rest of the ship.
Answer:A. mast is seen before the hull.