Answer:
The correct matches are-
1. a portion of a large group - Sample
Sample is a part of population, considered for surveys.
2. choosing a sample so that every member has an equal chance of being chosen - Random sample
Random sample is non biased way of sampling where each member has equal chances of participating in the survey.
3. choosing a sample from people who are under 15 years old - Biased sample
Biased samples produce biased results. These are based on specific criteria and are not random.
4. using the responses of a small group to make conclusions about the large group - Estimating from a sample
Estimations are rough conclusions made from collecting responses.