Question

researchers call random radio listeners on the phone to rank five different popular songs. this research helps radio stations decide which songs to play more often. this method of gathering data is classified as
a census.
a sample survey.
an experiment.
an observational study.

Explanation:

The researchers are calling random radio listeners (a sample) to gather data about song preferences. A sample survey involves collecting data from a subset (sample) of a population. A census would involve all radio listeners, an experiment involves manipulating variables, and an observational study observes without intervention. So this is a sample survey.

Answer:

a sample survey.