Emissions of all the following have declined since 1970 EXCEPT A
Small Particulate Matter (PM10)
B. sulfur dioxide
C. ground level ozone
D. nitrogen dioxide
E. carbon dioxide

What major factors play a role in global warming? 1. human activity and normal climate conditions 2. natural factors and human activity 3. normal climate conditions and abnormal human activities 4. abnormal human activities and natural factors

If a population is growing quickly in a small area then what must increase as well

If you were a casual recreational hiker with young children, which of the following trails would be least strenuous for a leisurely family outing? a. merced lake trail b. mirror lake loop trail. c. tenaya lake and tuolumne meadows trail d. el capitan trail