What diagnosing conduct disorder, which of the following symptoms must occur prior to 13 years of age? A. Staying out all night b. Committing a break in c. Mistreating an animal d. Destruction of property

C. Mistreating an animal.

The correct answer is c. Mistreating an animal.

To diagnose conduct disorder, at least one symptom must occur prior to 13 years of age. Mistreating an animal is one of the symptoms listed in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) as a criterion for conduct disorder.