Objects moving along a circular path have a centripetal acceleration provided by a net force directed toward the center. Identify the force(s) providing the centripetal acceleration in each of these cases: a planet in circular orbit around its sun; a car going around an unbanked, circular turn; a rock tied to a string and swung in a vertical circle, as it passes through its highest point; and a dry sock in a clothes dryer as it spins in a horizontal circle. (Select all that apply.)