What could have triggered mass extinctions of species in the past?

$Eichhornia$ $crassipes$ is a

Match List-$I$ and List-$II$ and choose the correct option.

List-$I$	List-$II$
$(i)$ Dodo	$(p)$ Africa
$(ii)$ Quagga	$(q)$ Mauritius
$(iii)$ Thylacine	$(r)$ Russia
$(iv)$ Steller's sea cow	$(s)$ Australia

Which of the following is the most important cause for the extinction of animals and plants?

One of the endangered species of Indian medicinal plants is that of

Of the four major causes for the loss of biodiversity (Alien species invasion,habitat loss and fragmentation,over-exploitation,and co-extinctions),which according to you is the major cause for the loss of biodiversity? Give reasons in support.