How many biodiversity hotspots have been identified by Norman Myers globally to date?

Who explained the species-area relationship?

$(1)$ 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 $\underline C\%$.

The dolphin found in Chilka lake is

Approximately $.........$ plant species are used by indigenous people around the world in traditional medicines. (in $,000$)

Which of the following regions is a biodiversity hotspot in India?