The correct option is C Guide pollen tube towards micropyle
Any ovular structure which helps in directing the growth of pollen tube towards the micropyle is generally referred to as obturator. Obturators exhibit great variation in their origin, morphology, anatomy and extent of development. They may originate from placenta or funiculus or both. The most common type of obturator is one formed by local swelling of the funiculus as in families Acanthaceae, Anacardiaceae, Lamiaceae, Magnoliaceae etc.