The correct option is B Fatty substance
The wall of the mature pollen grain is stratified. It comprises two principal layers the internal layer is called as intine and the outer layer is called as exine. The intine is pecto-cellulosic in nature. The exine is chiefly composed of a class of material called as sporopollenin. Chemical analysis has revealed that it is a mixture of biopolymers, containing long chain fatty acids, phenylpropanoids, phenolic compounds and carotenoids. It is derived from carotenoids by oxidative polymerization. Sporopollenin is resistant to physical and biological decomposition. Because of this property, the pollen grain walls are often preserved for long periods in fossil deposits.