For each of the following, tell whether or not you would expect it to have a strong seasonal component and why.
a. Sales of colorful wrapping paper, recorded monthly.
b. The number of air travelers to Hawaii from Chicago, recorded monthly.
c. The S&P 500 stock market index, recorded daily. Assume that the stock market is efficient, so that any foreseeable trends have already been eliminated through the action of large investors attempting to profit from them.