Suppose a student named Marcus wants to learn about the sleeping habits of students in his class. Marcus wants to collect data from his classmates to learn how many hours of sleep his classmates get. He then wants to process this data with a computer and visualize it in a Histogram. Which of the following would be the best technique for Marcus to collect this data?

a. Marcus should ask each of his classmates to write down on a piece of paper how many hours of sleep they get per night and hand the paper to him.
b. Marcus should have them download an app that tracks their phone geolocation and activity so he can see when their phones are in their rooms and not being used. From this data he can figure out how long each student sleeps.