Which of the following time series would be an excellent candidate if you were looking to show a trend in the data?
a) total solar power generated at a certain site each month over a span of years
b) total solar power generated at a certain site each year over a span of several years
c) total solar power generated each noon minute over the course of an hour, as a sequence of storm clouds pass overhead
d) total solar power generated at a certain site each day, january-july