The Study Guide states that in an HA cluster, ''As well as normal scanning duties, the primary node also manages the cluster, distributes jobs, and gathers the verdicts.'' It also says that ''The worker nodes provide load balancing. The primary node distributes scan jobs to the worker nodes.''

From those official statements, the primary node is not just a coordinator. It also performs normal scanning duties itself, while distributing scan jobs across worker nodes for load balancing. That rules out A, because the secondary node is for failover, not normal job distribution. It rules out C, because the primary is not restricted to itself only. It also rules out D, because the primary can still perform scanning duties and is not limited to sending all jobs only to workers. Therefore, when the primary receives MTA jobs, the correct behavior is that it distributes the MTA jobs to itself or to worker nodes.