What proportion of adults experience serious mental health problems?

• A. 5
• B. 13
• C. 17
• D. 25

Answer: (C)

The statement tests how common mental health problems are among adults within a year. In public health surveys, about 17% of adults experience some mental health problem in a given year—roughly one in six. That makes 17% the best match for this question, since it reflects the commonly cited annual prevalence of mental health issues in the adult population.

Keep in mind there’s a distinction: a smaller share—around 5%—reflects serious mental illness, while 25% would be higher than typical annual estimates for mental health problems. So 17% sits in the widely used range for annual prevalence, explaining why it’s the correct choice.