(b) : Golden rice is a transgenic variety of rice (Oryza sativa) which contains good quantities of $\beta$-arotene (provitamin $A$ ­ inactive state of vitamin $A$ ). $\beta$-­carotene is a principal source of vitamin $A$. Since the grains of this rice is yellow in colour due to $\beta$-­carotene and commonly called golden rice.