Anyone know the 4 digit code?

The respiratory system removes oxygen and water from the body. select the best answer from the choices provided t f

Idon’t quite understand this problem

Students design a model roller-coaster track. they place a rubber ball at the highest point on the track and let it go. the ball rolls along the track pulled only by the force of gravity. eventually, it comes to a stop. which change to the design will result in the ball moving the greatest distance?