Compound A is an optically active mixed triglyceride, for which the following apply: a) contains three different fatty acids and has molecular formula C55H10406. b) by catalytic hydrogenation it is converted into a new triglyceride, B, which is not optically active. c) the transesterification of B under the influence of methanol in an acidic environment gives three products (C, D and glycerol) of which C has a total of 21 carbon atoms. Determine the two possible structures of A and the structures of B, C and D.