Final answer:
The received bits '10100111' indicate an error in transmission when using even parity, as the number of 1s is odd. The correct data cannot be defined without the inclusion or exclusion of a parity bit in the sequence.
Step-by-step explanation:
The question relates to digital data transmission and parity checking, which is a method used to detect errors in data communication. In the context of the received bits '10100111', the even parity method requires that the total number of 1s in the data should be even. We can see that there are five 1s in the sequence. Since five is an odd number, this indicates that there has been an error in the transmission if we are expecting even parity, because with even parity, the number of 1s should be even.
If the sequence includes the parity bit and the expectation is for the sequence to have an even number of 1s including the parity bit, then the data transmitted is '1010011' (without the last bit) since the 1s count would then be even when the parity bit (last digit) is included. However, if the parity bit has not yet been included and we need to make the count even, then an error has occurred, as we cannot define the correct 7-bit sequence and need to request the data to be retransmitted.