Why do small molecular substances typically not conduct electricity?

The correct option is They lack free-moving charged particles.. This answer is correct because it matches the approved learning objective to explain why larger molecules tend to have higher melting points and boiling points than smaller molecules in the subtopic Properties of small molecules.

The correct option is They lack free-moving charged particles.. They lack free-moving charged particles. is correct because it directly supports the approved learning objective to explain why larger molecules tend to have higher melting points and boiling points than smaller molecules. This belongs to the subtopic Properties of small molecules within How bonding and structure are related to the properties of substances, so the explanation must stay tied to that curriculum context. The other options are incorrect because they either do not answer this learning objective, use a vague statement, or move away from Properties of small molecules.