im guessing k12? :)
i would say A probably, i actually was just watching a video about climate change by Bill Nye the Science Guy
i'll draw a picture just in case im wrong.
|dw:1432766025219:dw|as you can see, the lines represent heat from the sun, as it hits the earth. it hits the equator almost dead on, so thats why places around the equator are usually tropical.
it also touches the southern and northern hemispheres, so it gets cooler. it barely touches the north and south poles, so its much cooler there.
i hope my answer helped and i hope you get the question right :3
ill tell u when im done