The molecular formulae for four compounds are shown below. 1. $\mathrm{CH_4}$ 2. $\mathrm{C_2H_6}$ 3. $\mathrm{C_3H_8}$ 4. $\mathrm{C_3H_6}$ Which of these molecular formulae are also the empirical formulae of the compounds?
- A1 and 2
- B1 and 3
- C2 and 4
- D3 and 4