Which of the following is a waterborne disease?

Concept: A waterborne disease is one caused by pathogenic microorganisms that spread through water contaminated with faecal matter, typically via the faecal-oral route, when such contaminated water is used for drinking, cooking, or washing.

Application: Hepatitis, specifically Hepatitis A and Hepatitis E, is transmitted primarily through water and food contaminated with the virus, which is exactly this faecal-oral, water-based transmission route.

Cross-check against the other options:

• Measles spreads through airborne respiratory droplets, not through water.

• Malaria spreads through the bite of an infected mosquito (a vector-borne route), not through water.

• "Lung disease" is a broad umbrella term for respiratory conditions with varied causes; it is not a single disease defined by a water-based transmission route.

Note: other hepatitis types, such as Hepatitis B, C, and D, spread mainly through blood, body fluids, or perinatal transmission rather than water; among the given options, Hepatitis is still the one that includes a recognised water-transmitted form (A/E), which is why it is the intended answer here.

Therefore, Hepatitis is the correct answer, as it is the only option among these that is transmitted through contaminated water.