What Reasons Does Witherington Propose as Reasons for the Possibility

What reasons does Witherington propose as reasons for the possibility of false teachers slipping into church services and creating mayhem?

A) Christians had always been encouraged to welcome strangers and offer them hospitality in their homes.
B) Strangers with strange beliefs were seen as potential converts because of the evangelistic nature of Christianity.
C) Both a and b
D) None of the above