Answer:
Quantitative
Explanation:
In research, the term quantitative research refers to the type of research that involves gathering data that is quantifiable, in other words, that it can be measured in an objective way and expressed in numbers.
In this example, researchers measure children's IQ by using IQ tests, therefore, they are gathering data that can be measure and expressed in numbers <u>(IQ is a number).</u> Therefore, they are using quantitative research.