Researchers isolated an unknown substance, X, from rabbit muscle. They determined its structure from the following observations and experiments. (a) Qualitative analysis showed that X was composed entirely of C, H, and O. A weighed sample of X was completely oxidized, and the H2O and CO2 produced were measured. This quantitative analysis revealed that X contained 40.00% C, 6.71% H, and 53.29% O by weight. (b) The molecular mass of X, as determined by mass spectrometry, was 90.00 atomic mass units (u). (c) Infrared spectroscopy showed that X contained one double bond. (d) X dissolved readily in water, and the solution demonstrated optical activity when tested in a polarimeter. (e) The aqueous solution of X is acidic. What is the empirical formula of X