Which of the following is a difference between a time-synchronized OTP and a challengebased OTP? a. Only time-synchronized OTPs use tokens. b. The user must enter the challenge into the token with a...

Which of the following is a difference between a time-synchronized OTP and a challengebased OTP?

a. Only time-synchronized OTPs use tokens.

b. The user must enter the challenge into the token with a challenge-based OTP.

c. Challenge-based OTPs use authentication servers while time-synchronized OTPs

do not.

d. Time-synchronized OTPs cannot be used with Web accounts while challenge-based

OTPs can.