The compound R is: RRRABCD?

Aldol condensation of isobutyraldehyde (P) with formaldehyde (Q) gives 3-hydroxy-2,2-dimethylpropanal (R). Addition of a molecule of HCN to the aldehyde group gives cyanohydrin 2,4-dihydroxy-3,3-dimethylbutanenitrile (S). Acidification results in the formation of 3-hydroxy-4,4-dimethyldihydrofuran-2(3H)-one. Option A is correct.