The correct option is C Duranta
The thorn is a hard, straight and pointed structure. In Bougainvillea and Duranta, the axillary bud is modified into a thorn. The thorn sometimes bears leaves, flowers and fruits as seen in Duranta and Pomegranate. The thorns not only check the rate of transpiration but also protect the plants from herbivore animals. For example, Carissa, Duranta and Citrus.
Thus, the correct answer is option C.