Orgoreview

Compound I, molecular formula C₅H₁₁Br, undergoes potassium t-butoxide-catalyzed elimination to give compound II, molecular formula C₅H₁₀, as the major product.  The ¹H-NMR spectrum of I shows signals at δ 1.01 (d, 6H), 1.79 (d, 3H), 2.24 (m, 1H), 3.59 (dq, 1H). 

Which one of the following compounds is compound II?