Answer: External validity.
Step-by-step explanation:
When any research is done, then there are two possibility of its validation. One is internal validation and other is external validation.
The internal validation refers to the condition in which the conclusion of the study is within context of the particular study.
The external validation refers to the condition in which the conclusion of the study is out of the context.
Here, The study was performed only on the eating disorders in the adolescent boys but the conclusion included other males of different age groups.