A short fragment of a polymer chain (end groups shown) is drawn. Which of the structures shown, given as two molecules, are the products of complete hydrolysis of all carbonate links?

The links are carbonate groups, -O-CO-O-, in poly(propylene carbonate), made from propylene oxide and carbon dioxide. Hydrolysis of each carbonate gives two alcohol groups and carbon dioxide (via carbonic acid). The diol unit is propane-1,2-diol, so the products are propane-1,2-diol and carbon dioxide. The other options have the wrong diol or the wrong one-carbon product.