A histogram can be built without any labels, but it would be very hard to interpret it. You generally want to avoid it. You've collected two datasets: one represents the number of books your friends read per year, and the other one shows the number of films they've seen. They are called books and films. You need to draw a clear histogram with a title, labels, and a legend.
Match each function to its' argument. Choose a blank line if the function has no arguments.
The empty option on the right means that the corresponding function takes no arguments.