The correct answer is B) Corrective maintenance. Corrective maintenance is a reactive approach where maintenance is performed only after a failure or problem has occurred. This is in contrast to proactive maintenance approaches like planned maintenance, predictive maintenance, and condition-based maintenance, where maintenance is performed to prevent or anticipate failures before they happen. The other options are incorrect because they represent proactive approaches to maintenance, where steps are taken to monitor equipment condition and perform maintenance on a scheduled or as-needed basis, rather than waiting for a failure to occur.