The common mode output voltage with CMRR=65dB is determined as follows: CMRR in decibels = 20log(differential gain/common mode gain). With CMRR=65dB, this converts to a linear ratio of approximately 1778. The common mode output voltage represents the amount of common mode signal that appears at the output despite the rejection. For the given problem, the correct answer is (b) 281.17mV, which indicates the voltage that leaks through to the output when a common mode signal is applied due to the finite CMRR of the op-amp. This is a practical limitation of real op-amps that must be accounted for in precision circuits.