In a study of 987 high school students performed by a research group, participants were asked how frequently they wear seat belts while riding in a car. 75% of respondents said "always".
Identify the sample and the population in the study.

Sample: All students in the country; Population: The 987 students surveyed.

Sample: All students at Johnson Research Group; Population: Only the students who participated.

Sample: The 75% of students who said "always"; Population: All teenagers in the country.

Sample: The 987 high school students surveyed; Population: All high school students.