The correct answer is D) dumped to a condenser. When the machinery plant's steam production exceeds the demand, the excess steam needs to be disposed of. Dumping the excess steam to a condenser is the appropriate method, as this allows the steam to be condensed back into water, which can then be recycled or discharged overboard as necessary. This is a common practice in marine steam plant operations to maintain the proper pressure and temperature balance in the system. The other options are incorrect because: A) re-circulating to the first stage articulator would not be an effective way to manage the excess steam; B) venting to the atmosphere would be wasteful and potentially hazardous; and C) jettisoning overboard below the waterline would not be a safe or practical solution for disposing of the excess steam.