Select the single best answer. compound a exhibits two singlets in its 1h nmr spectrum at 2.64 and 3.69 ppm and the ratio of the absorbing signals is 2: 3. compound b exhibits two singlets in its 1h nmr spectrum at 2.09 and 4.27 ppm and the ratio of the absorbing signals is 3: 2. which compound corresponds to dimethyl succinate and which compound corresponds to ethylene diacetate? 1455a 1455b dimethyl succinate ethylene diacetate?