The correct options are
B low
D weak
Intermolecular force refers to the force of attraction between the molecules that make up that matter. As the intermolecular force between the molecules in a substance increase, more energy is required to break this force of attraction and vice versa. This results in an increase in the melting point of the substance.
Covalent compounds have weak intermolecular forces between its molecules and hence, have low melting points.