A substance that conducts electricity when dissolved in solution.

• A. Ileum
• B. Pernicious anemia
• C. Pyelonephritis
• D. Electrolyte

Answer: (D)

A substance that conducts electricity when dissolved in solution is an electrolyte. The key idea is that electrolytes dissociate into ions in water, producing charged particles that can move freely. When an electric field is applied, these ions carry the current, allowing the solution to conduct electricity. This is why salts, acids, and bases are classic electrolytes, and in the body, ions like sodium, potassium, calcium, and chloride function as electrolytes to enable nerve signals and muscle activity.

The other terms describe a body structure or conditions, not a substance that, when dissolved, forms ions to conduct electricity. Ileum is part of the small intestine, pernicious anemia is a vitamin B12 deficiency condition, and pyelonephritis is a kidney infection.