Race organizers want to survey the participating runners on the quality of the running course. Which of the following uses systematic random sampling?

Select the first 15 finishers and the last 15 finishers to take the survey.
Randomly select 15% of the male participants and 15% of the female participants.
Select the 5th finisher (with the number 5 being randomly chosen) to survey, then survey every 15th finisher after that.
Sort all of the runners’ names alphabetically, then randomly choose 2 letters and survey all participants whose last name begins with one of those letters.

Select the first 15 finishers and the last 15 finishers to take the survey.