Atoy rocket was launched from the ground. the function f(x) = -16x2 + 160x shows the height of the rocket f(x), in feet, from the ground at time x seconds.
what is the axis of symmetry of the graph of f(x), and what does it represent?

these are the choices:
x = 10; it takes 10 seconds to reach the maximum height and 10 seconds to fall back to the ground
x = 10; it takes 10 seconds to reach the maximum height and 20 seconds to fall back to the ground
x = 5; it takes 5 seconds to reach the maximum height and 10 seconds to fall back to the ground
x = 5; it takes 5 seconds to reach the maximum height and 5 seconds to fall back to the ground