Each of the following compounds is characterized by a 1H NMR spectrum that consists of two peaks,

Question:

Each of the following compounds is characterized by a 1H NMR spectrum that consists of two peaks, both singlets, having the chemical shifts indicated. Identify each compound.
(a) C6H8; δ 2.7 ppm (4H) and 5.6 ppm (4H)
(b) C5H11Br; δ 1.1 ppm (9H) and 3.3 ppm (2H)
(c) C6H12O; δ 1.1 ppm (9H) and 2.1 ppm (3H)
(d) C6H10O2; δ 2.2 ppm (6H) and 2.7 ppm (4H)