In Luffa the tendrils are modified
Stem tendrils are of four types:
(a) Axillary tendrils-e.g., Passiflora
(b) Extra-axillary tendrils-e.g., Cucurbita, Luffa
(c) Leaf-opposed or the Apical bud tendrils, for example, Grapevine (Vitis)
(d) Floral bud or the Inflorescence tendrils – for example, Antigonon, Cardiospermum (Balloon vine)
Thus the correct option is C.