For each of the following time series, do you think the long-term trend would be positive, negative,

Question:

For each of the following time series, do you think the long-term trend would be positive, negative, or nonexistent?
a. The cost of a loaf of bread measured monthly from 1960 to the present month.
b. The temperature in Boston measured at noon on the first day of each month from 1960 to the present month.
c. The price of a basic computer, adjusted for inflation, measured monthly from 1970 to 2012.
d. The number of personal computers sold in the United States measured monthly from 1970 to 2012.