37. A container filled with water rests on a horizontal floor. If the container moves to the right with a constant acceleration a, the water surface will tilt. Given the acceleration due to gravity is g, which of the following equations is satisfied by the angle θ between the water surface and the horizontal? (A) sin θ = a/g (B) cos θ = a/g (C) tan θ = a/g (D) tan θ = g/a