D.
For example in New York, the Erie Canal was dug to connect Lake Erie in western NY to Hudson River in eastern side of NY.
Waterway built to allow ship travel vs. slower overland wagons etc.
Ocean warming provides a good example of a potential positive feedback mechanism.
The placebo effect is a procedure in which a patient is made to believe that a drug has a direct on the person. Therefore improving his/her symptoms from the said disease that he/she is experiencing. It is directly injecting or making a procedure using alternatives. The idea is that the patient would believe such measures were done and that they will be cured from their diseases. There are no video clips available on you questions but I hope this helps.
reason behind Ida B. Wells' call for blacks to leave Memphis. A mob destroyed Wells' newspaper while Wells was out of town. Forced to remain in the North, Wells launched a national crusade against lynching that would capture the attention of the nation and Europe.
