In an effort to identify it, an unknown compound, U, was subjected to extensive spectroscopic analysis. In addition, the mass spectrum of compound U was aquired. A molecular ion peak was observed at m/z = 166, and the molecular formula for compound U was thereby determined to be C9H10O3. A peak at m/z = 121 was by far the most intense peak in the mass spectrum. Determine the structure of compound U. Be sure to include a concise discussion of the reasoning. Construct tables summarizing the IR and 1H NMR data, and assign the peaks in the IR and NMR spectra to the appropriate structural elements in U. Explain the appearance of the base peak at m/z = 121 in the mass spectrum.