Which of the following represents time-series data?

A) The length of time each of the top 100 stocks have been available on the NYSE.
B) The most popular time of year that people purchase the top 100 stocks on the NYSE.
C) The value of the #1 stock on the NYSE each month over a one-year period.
D) All of these choices are true.

Time-series data refers to data that is collected over a period of time and shows patterns or trends over that time period. Option C represents the value of the #1 stock on the NYSE over a one-year period, which is collected over time and shows a pattern or trend, therefore it represents time-series data. Options A and B are both related to the top 100 stocks on the NYSE, but do not involve collecting data over a period of time, therefore they do not represent time-series data. Option D is incorrect, as only option C represents time-series data.