What percentage of people 85 and older have Alzheimer's disease?

When a drug user experiences withdrawal symptoms and takes the drug to alleviate those symptoms, this is:

a. negative punishment. b. negative reinforcement. c. positive punishment. d. positive reinforcement.

People have a significant impact on both natural and constructed environments and can alter natural cycles, animal populations, and the very face of the Earth

Indicate whether the statement is true or false