Karen Is Interested in Studying the Prevalence of Suicidal Ideation

Karen is interested in studying the prevalence of suicidal ideation in her clients who are suffering from schizophrenia. She selects a random sample from the list of clients she had treated in the previous year. Although she engages in the random selection of participants, when she begins to analyze her data, she realizes that the clients in her sample are generally younger than those who did not participate in the study. This finding:

A) impacts the generalizability of the results to all her clients who are suffering from schizophrenia.
B) indicates that instead of random sampling, she chose participants in an orderly way from the target population.
C) confirms the systematical similarity of Karen's sample to the population.
D) shows that each observation in the population has an equal chance of being selected.