The extinction of the passenger pigeon was due to

How many of the following are causes of biodiversity losses $:-$
$(a)$ Habitat loss
$(b)$ Over-exploitation
$(c)$ Alien species invasion
$(d)$ Co-extinction

These are regarded as major causes of biodiversity loss:
$A$. Over-exploitation $B$. Co-extinction $C$. Mutation $D$. Habitat loss and fragmentation $E$. Migration
Choose the correct option:

Among the following plants,which one would you consider an endangered plant due to over-exploitation?

Among 'The Evil Quartet',which one is considered the most important cause driving extinction of species?

At high altitudes,birds become rare or extinct. The plants which may disappear along with them are: