What classes of monomers could be used to make polymers known as polyesters?

Question

(a) acid anhydrides and aldehydes
(b) dihydroxy alcohols and dicarboxylic acids
(c) dihydroxy alcohols and glycols
(d) ketones and acohols

Answer 1

Obviously B

Answer 2

B, diols and dioic acids. polyesters are polymers of a repeating backbone of ester linkages. these are made from carboxylic acids and alcohols. to make a long chain, you need 2types of molecules: dicarboxylic acids and diols. or if you plan on using 1 molecule only, this molecule has to have at least 1 alcohol group and 1 acid group. A and D are definitely wrong. C is a trick because dihydroxy alcohols and glycols are the same thing.