Which of the following describes a surplus?

What does collaboration mean? ? and what is your favorite food? ?

This is science by the way which of the following is an example of an environmental pressure a. the air pressure in the atmosphere b. a lake that is gradually running out of water c. a fight between two members of the same species d. breeding between two members of the same species

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