Atmospheric lead concentrations declined between 1975 and 1982 in response to
A. reduced levels of lead in lead-based paints.
B. reductions in the lead content of gasoline.
C. decreased volcanic activity.
D. reductions in the lead content of smokestack emissions.
Answer: B
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A continental ice sheet once covered most of Canada
Indicate whether the statement is true or false
Which is older - rock unit J or H?
What will be an ideal response?
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