Why would you expect most U.S. common stocks to have positive covariances? Give an example of two

Question:

Why would you expect most U.S. common to have positive covariances? Give an example of two that you would expect to have a very high positive covariance. Give an example of two that you would expect to have a very low positive (or even negative) covariance.
Stocks
Stocks or shares are generally equity instruments that provide the largest source of raising funds in any public or private listed company's. The instruments are issued on a stock exchange from where a large number of general public who are willing...