I believe the answer is: naturalistic observation
Naturalistic observation is being done without any form of variable manipulation from the researchers. The purpose of such observation is to make the result of the study represent the actual condition as close as possible. Usually only applicable for qualitative data.
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Variables are the term of concepts in a study, such as the average age of a person upon acquiring his or her first job and the average salary he or she was paid for that job.
Answer: Option A
<u>Explanation:
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A variable is a feature, number or quantity that can be measured or counted. A variable can also be called a data element. Examples of variables are person's age, category of gender, company revenue and expenditures, birth country, capital expenditure, grade class, eye color and vehicle type.
Salary is some amount of money paid to the employee from an employer in a company. So, here in the given situation, the average person’s income come under the term variable (can be counted).