The electron-impact mass spectrum (EI-MS) of 5-methyl-3-heptanone (C8H16O) is shown below.

Briefly explain the following: (a) the relative intensities of the peaks at m/z=128 and 129 . (b) the bond cleavage process that produces the fragment ion peak at m/z=99. (c) the bond cleavage process that produces the fragment ion peak at m/z=57 (d) the bond cleavage process that produces the fragment ion peak at m/z=72