Final answer:
The collected blood type and heart rate data by the nurse is a sample because it comes from a subset of all hospital patients and therefore cannot represent the entire hospital population.
Step-by-step explanation:
The data set collected by the nurse represents a sample because it is collected from a subset of a hospital, which has many more patients. It is impossible to assume that these five patients' blood types and heart rates represent all past, present, and future patients of the hospital. If every patient's data were collected, it would constitute a population data set. Since only a manageably small group's data is collected for practical reasons, such as the nurse's five patients, it represents a sample of the larger group. This sample could be used to make inferences about the larger population within the hospital with the understanding that there is a margin of error due to it not being the entire population.
Therefore, the correct answer to whether the data set collected is a population or a sample is: d. The data set collected is a sample because it is a subset of the hospital.