Correct option is C
At 6 cm, the patient is in active phase of labor. If contractions are regular (every 5 min), next step is monitoring FHR + contractions, not intervention.
Explanation of options: (a) ✘ Cesarean is indicated for arrest disorders, not here. (b) ✘ Augmentation only if contractions inadequate, but here they are adequate. (c) ✔ Correct; continuous monitoring is standard active labor management. (d) ✘ Episiotomy is done in 2nd stage, not active phase.