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