Which of the following was not an advancement created during the Han dynasty? A. the design of new water clocks and sun dials
B. the invention of paper
C. the creation of a new kind of seismograph
D. the creation of China's first system of writing

Martha participates in a research study in order to receive extra credit for her psychology class. when she arrives in the research office she is given a can of what looks and tastes like beer, but which actually contains no alcohol. in the adjoining room martha's classmate karen is also participating in the study. karen receives a can of alcoholic beer. if the experiment was designed to test the effects of alcohol on concentration, then who is exposed to the independent variable?