Answer: Abigail falsely claims that she did witchcraft along with the girls in the woods, since Tituba's confession proved that, If she said it, the sin would be forgiven.
Explanation: When Reverend Hale examines Betty, he finds out the truth about the witchcraft that she and other girls did in the woods. Since it was a forbidden act for the townspeople, the Reverend started looking for more culprits. Tituba decided to proclaim herself as a participant of said witchcraft, and Abigail noticed that by doing this, people were being forgiven and not punished; Hence, she falsely claimed to be a member of the act as well and acted guilty.