What is the medicine prescribed for the patient with social security number 999-94-3751?
medicine prescribed refers to DESCRIPTION from medications; social security number 999-94-3751 refers to ssn = '999-94-3751';
SELECT T1.DESCRIPTION FROM medications AS T1 INNER JOIN patients AS T2 ON T1.PATIENT = T2.patient WHERE T2.ssn = '999-94-3751'