Which zone contains the headwaters of a stream system? A. transition zone.
B. source zone.
C. floodplain zone.
D. delta zone.
E. littoral zone.

Of the pollutants that form acids in the atmosphere, which is easiest to reduce? a. sulfur dioxide b. nitrogen dioxide c. ozone d. carbon monoxide

Witch type of microscope is used to view very small cell components like proteins and dna?

Factors that can increase mutation rates a. high temps b. low temps c. food additives d. uv rays