Which kind of action is a cause of air pollution?
a. poisons are released into a major river.
b. gasoline is burned by a car engine.
c. trash is dropped in a national wildlife preserve.
d. tuna are fished to extinction.

Scientists are conducting a study on the effectiveness of a new drug on memory loss. they are giving some of the test subjects the new drug to find out if it improves their long-term memory. which are possible limitations of this study? check all that apply. a) test subjects may want to participate in additional experiments. b) test subjects may think they should be paid more. c) test subjects may get bored and want to quit early. d) test subjects may have to travel during the experiment. e) test subjects may have full-time jobs. this is multiple choice. you for the !