Answer:
When discussing drought, one must have an understanding of aridity and the difference between the two. Aridity is defined, in meteorology and climatology, as "the degree to which a climate lacks effective, life-promoting moisture" (Glossary of Meteorology, American Meteorological Society). Drought is "a period of abnormally dry weather sufficiently long enough to cause a serious hydrological imbalance". Aridity is measured by comparing long-term average water supply (precipitation) to long-term average water demand (evapotranspiration). If demand is greater than supply, on average, then the climate is arid. Drought refers to the moisture balance that happens on a month-to-month (or more frequent) basis. If the water supply is less than water demand for a given month, then that month is abnormally dry; if there is a serious hydrological impact, then a drought is occurring that month. Aridity is permanent, while drought is temporary.
Answer: The correct requirement for a black hole to form is:
C. The star must be 10 to 28 times larger than Earth’s sun, and a supernova explosion must have occurred.
Explanation: The least star that is larger than the sun is 10 times larger and a supernova explosion would have happen before a black hole to form.