Final answer:
Sacral counterpressure is the recommended intervention to alleviate low back pain due to persistent occiput posterior presentation during active labor.
Step-by-step explanation:
The student is asking which nonpharmacological nursing intervention would best alleviate low back pain due to persistent occiput posterior presentation during active labor. Among the listed options, the most effective intervention specifically for the described situation would be sacral counterpressure. This technique involves applying steady pressure to the lower back, counteracting the stress and pain caused by the baby's head pressing against the mother's back. Other interventions like hydrotherapy, unless contraindicated, can also provide significant pain relief during labor. Interventions such as abdominal effleurage and back rubs may offer general comfort, but sacral counterpressure is directly targeted at alleviating back pain associated with this fetal position.