While interviewing Joe, Dr. Willard discovers that Joe has a genetic predisposition for schizophrenia because his uncle and mother had schizophrenia. Dr. Willard also believes the fact that Joe was homeless for several months after being expelled from school and "disowned" by his parents triggered his schizophrenia. Dr. Willard probably follows the ____________ model of psychological disorders

'Diathesis-stress' model is demonstrated as the theory which asserts that the mental disorders are a product of either genetic predisposition or biological proneness for the disorder amalgamated with stressful conditions that play an advanced role in facilitating the disorder.

As per the given description, Willard more likely follows the 'diathesis-stress' model of psychological disorders as he considers Joe's 'genetic predisposition'(for schizophrenia which he inherited from his mother or uncle) combined with the stressful situations(remain homeless, being expelled from the school, disowned by his parents, etc.) together contributed to triggering the same disorder 'schizophrenia' in him. Thus, option A is the correct answer.