Please help! I need to submit this in 20 minutes!

Anyone knows answer for code.org unit 3: intro to programming, lesson 7: apis and function parameters, bubble 11. !

Why are radio observatories located in valleys far away from urban centers? a. to shield them from electromagnetic interference b. to avoid sound pollution c. to avoid disturbing people living in the city d. to shield them from water vapor

This is a major archaeological site that was once a regional center to the mayan empire in ancient mesoamerica.