The greatest progress in reducing atmospheric levels of lead ...

[nevelica]

The greatest progress in reducing atmospheric levels of lead pollution resulted from
 
  A) the elimination of leaded gas.
  B) the switch from lead to graphite in pencils.
  C) the development of new types of batteries that use lithium instead of lead.
  D) new types of lead scrubbers on smokestacks that removed lead from the air.

Question 2

Increases in ocean temperatures often result in coral bleaching, in which
 
  A) the symbiotic relationship between corals and their algae is disrupted.
  B) the calcium carbonate of corals is dissolved away, leaving only the soft animals behind.
  C) the water becomes so cloudy that no light can reach the symbiotic algae in corals.
  D) high levels of chlorine are released from the corals, killing the fish that swim by.

[mcomstock09]

Answer to Question 1

A

Answer to Question 2

A