Following are spectroscopic and analytical characteristics for an unknown compound. Propose a structure. Empirical formula: C₈H₁₆O. ¹H NMR: δ = 0.90 (t, 3 H), 1.0 – 1.6 (m, 8 H), 2.05 (s, 3 H), and 2.25 (t, 2 H) ppm. IR: 1715 cm^-1 . UV: λ_max(ϵ) 5 280(15) nm. MS: m/z 5 128 (M^+• ); intensity of (M + 1)⁺ peak is 9% of M^+• peak; important fragments are at m/z = 113 (M - 15)⁺ m/z = 85 (M - 43)⁺, m/z = 71 (M - 57)⁺, m/z = 58 (M - 70)⁺ (the second largest peak), and m/z = 43 (M - 85)⁺ (the base peak).