Which of the following statements is true? a. the nitrogen cycle is the most important cycle for life. b. the oxygen cycle is the least important cycle for life. c. life can be sustained without any of the cycles for life present. d. all cycles of matter are equally important for life to be sustained. select the best answer from the choices provided

When an object is heated it contracts. a. true b. false

How do you tell if someone actually cares about you? and just say they do?

Which statement is true if the refractive index of medium a is greater than that of medium b? a. total internal reflection is possible when light travels from air to medium b to medium a. b. total internal reflection is possible when light travels from medium a to medium b. c. total internal reflection is possible when light travels from medium b to medium a. d. total internal reflection is possible when light travels from air to medium a. e. total internal reflection is possible when light travels from air to medium b.