Plz help • Motor driven plow

• Electric lights

• Sewer system

• Vaccines

What do these technologies have in common?
A.
They are all very expensive to make.
B.
They all help improve quality of life.
C.
They are only used to help poor people.
D.
They are all made from natural resources.

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 !