Q: Which is a reason for Arkansas having multiple seasons? ----

A: the tilt of Earth's axis

Q: What is the outermost structure in a plant cell? ----

A: cell wall

Q: This in turn causes the average temperature on Earth to rise. Which of the following observations supports that theory? ----

A: Carbon dioxide in the upper atmosphere absorbs and re-emits heat radiated from Earth's surface.

Q: Harmful ultraviolet rays from the Sun are primarily absorbed by ----
A: ozone.