59. An unknown hydrocarbon shows a parent peak on the mass spectra at m/z = 86. There is no evidence of absorption fromvisible or UV spectra. The IR shows no major absorption outside the C-H stretch and bending vibration. The 1H NMRreveals a singlet at δ 0.9 (9H), a triplet at 0.98 (3H) and a quartet at 1.6 (2H). Which compound below best fits thedescription?