Compound A has prominent infrared absorptions at 1050,1786, and 1852cm1 and shows a single absorption in the proton NMR spectrum at 3.00. When heated gently with methanol, compound B,C5H8O4, is obtained. Compound B has IR absorptions at 25003000 (broad), 1730, and 1701cm1, and its proton NMR spectrum in D2O consists of resonances at 2.7 (complex splitting) and 3.7 (a singlet) in the intensity ratio 4:3. Give the structures A and B, omitting stereochemistry. Draw compound B. Draw hydrogens on oxygen where applicable