Throughout any introductory examination of ecosystems and environmental sustainability, the importance of human population numbers is cited. Currently, the world and U.S. populations are closest to ________.
A) 7 billion; 200 million
B) 7 billion; 300 million
C) 9 billion; 400 million
D) 7 billion; 500 million
E) 3.5 billion; 300 million
Question 2
How can radioactivity be used to determine the age of a rock?
What will be an ideal response?