Which of the following refers to the terms "residual error rate"?

• the number of bit errors per twenty four hours of continuous operation on an asynchronous line
• The probability that one or more errors will be undetected when an error detection scheme is used
• the probability that one or more errors will be detected when an error detection mechanism is used
• signal to noise ratio divided by the ratio of energy per bit to noise per hertz
• None of the above