The correct answer is b) peak corresponding to the most abundant ion.
In mass spectrometry, the base peak is defined as the peak that has the highest intensity in a mass spectrum. This means it corresponds to the most abundant ion detected during the analysis. It is important to note that the base peak does not necessarily have to correspond to the molecular ion, as there can be fragments of the molecule that are more abundant than the molecular ion. Consequently, options a) and c) can be false in many cases. Therefore, the most consistent truth about the base peak is that it represents the most abundant ion in the mass spectrum.