Which of the following types of natural disasters has no definite beginning…

Natural disasters are classified by how quickly they develop, into two broad categories: rapid-onset disasters, which strike suddenly and have a clearly identifiable start and end, and slow-onset disasters, which develop gradually over an extended period and have no single, clearly identifiable starting or ending point.

Among the given options, a drought is a slow-onset disaster: it results from a prolonged deficit of rainfall that accumulates gradually over weeks or months, and it eases just as gradually as conditions improve. Because there is no single triggering moment when a drought starts and no single moment when it ends -- only a gradual worsening or gradual recovery -- a drought has no definite beginning and end.

• Earthquakes: triggered by a sudden release of built-up tectonic stress; the event has a precise, recorded start (the moment the ground begins to shake) and end (when the shaking stops).

• Landslides: triggered by a specific slope-failure event (heavy rainfall, an earthquake, or excavation); the failure itself is a discrete, short-duration event with an identifiable onset.

• Hurricanes: tracked by meteorological agencies through a defined lifecycle, from formation to dissipation, so each event has a recorded start date and end date.

None of these three fits the description of a disaster with no definite beginning and end, which confirms Droughts as the correct answer.