(a) Grapes: Propagated through cuttings, where healthy vine segments are planted to develop new plants.
(b) Apple: Propagated through grafting, combining a rootstock and scion for improved yield and disease resistance.
(c) Brinjal: Propagated through seeds, which are sown directly or in nurseries for transplanting.
(d) Sugarcane: Propagated through stem cuttings, where mature cane segments with nodes are planted to grow new plants.
In the adjoining figure, TP and TQ are tangents drawn to a circle with centre O. If $\angle OPQ = 15^\circ$ and $\angle PTQ = \theta$, then find the value of $\sin 2\theta$. 