Final answer:
The salt which conducts electricity when melted or dissolved in water contains an ionic bond because the free movement of ions in these states allows for electrical conduction. So the correct answer is Option A.
Step-by-step explanation:
The white crystalline salt mentioned in the question conducts electricity when it is melted and when it is dissolved in water. This indicates the presence of mobile charged particles, which is characteristic of ionic compounds. Therefore, the type of bond this salt contains is an ionic bond (Option A).
Ionically bonded substances, such as table salt (sodium chloride), are made up of positive and negative ions. In a solid state, these ions form a rigid crystal lattice that does not conduct electricity. However, when melted or dissolved in water, the crystal lattice breaks down, allowing the ions to move freely and conduct electricity.