Simple molecules and covalent bonds — practice question

Ethane, $\text{C}_2\text{H}_6$, and ammonia, $\text{NH}_3$, both are covalent compounds. Their dot-and-cross diagrams are displayed. Which statements are true?

• A1, 2 and 3
• B1 and 2 only
• C1 and 3 only
• D2 and 3 only