Alexander von Humboldt described for the first time

Assertion : Diversity observed in the entire geographical area is called gamma diversity.
Reason : Biodiversity decreases from high altitude to low altitude.

Choose the incorrect pair for the Amazonian rain forest.

$(1)$ More than $\underline A\%$ of the drugs currently sold in the market worldwide are derived from plants.
$(2)$ Although all the biodiversity hotspots put together cover less than $\underline B\%$ of Earth's land area,the number of species they collectively harbour is extremely high,and strict protection of these hotspots could reduce the ongoing mass extinction by almost $\underline C\%$.

India has more than ........ genetically diverse strains of rice and more than ........ varieties of mango.

What is the total number of biodiversity hotspots in the world?