【单选题】
While troubleshooting a serial line problem, you enable ppp authentication debugging as shown below:<img src="https://nimg.ppkao.com/2018-07/longzhengxuan/2018073013573782199.jpg?sign=9dc178c8d321b64d4540780c97e3623c&t=62d73ffb" /><br /> <img src="https://nimg.ppkao.com/2018-07/longzhengxuan/2018073013574740148.jpg?sign=ece527bd637a6a464ea0cd374885ce10&t=62d73ffb" /><br /> Based on the command output above, what type of 'handshake' was used for PPP authentication?()
A、one-way
B、two-way
C、three-way
D、four-way
E、no handshakes required during authentication
F、None of the above