Determine whether the data set consisting of the number of books checked out by all library visitors during a month is a population or a sample. Explain your reasoning.

The data set is a population, as it includes information from every library visitor during the month

The data set is a population, but it only applies to a limited time period within the month

The data set is a sample, as it cannot represent all visitors in the library

The data set is a sample, as it only includes a small portion of the visitors