I believe the answer is: biological
The biological level in this context refers to the intellectual capabilities of the poor people. In their studies, they use iq level as the idependent behavior and economic wealth as the dependent behavior in order to see if there is a strong correlation between the two.
People began to glorify the arts and the human body during the Renaissance.
I would say a. Most flashbacks help readers get some background information on a character
(CERCLA) is a United States federal law designed to clean up sites contaminated with hazardous substances and pollutants.
Answer: The answer is Headset
Explanation: Headsets allow people to listen to music, videos, movies and any other kind of activity that provides sound without being a disturbance for other people. Generally, in quiet public settings such as libraries, certain workplaces, and internet cafes, the use of headsets is more than mandatory.