An open-topped conical tank with its apex pointing vertically downward is initially filled with water to a depth of \(H\). At time \(t = 0\), a small drain valve of area \(A_0\) at the bottom apex is opened, allowing water to drain out into the open air. The cross-sectional area of the water surface is always significantly greater than \(A_0\). Which of the following graphs best represents the water depth \(y\) as a function of time \(t\) from \(t = 0\) until the tank is completely empty?