Answer:
To look for a supernatural cause for Betty's illness.
Step-by-step explanation:
This is the advice that the doctor gives to Reverend Parris. At the beginning of the play, we learn that Betty is not waking up. Worried, Reverend Parris has sent for a doctor who can explain what is happening to Betty. The doctor, however, has no explanation for this behaviour. Instead, he advises Reverend Parris to look for a supernatural explanation. This contributes to creating the supernatural narratives that permeate the story.