Answer:
Doubt simply mean to suspect someone or something
Exposed means to catch someone red-handed and telling the rest how cruel or bad or good that person is
Plead means to apologize or seeking for something
Danforth needed a confession because the rule was that if they did not confess, they were hanged. If they did not confess and Danforth decided not to hang them, the town would become angry because 12 others were already hanged for not confessing.
Hope this helps!