It is now possible to breed plants and animals with desired characters through

Assertion $(A)$ : Vernalization is acceleration of subsequent flowering by low temperature treatment.

Reason $(R)$ : Site of vernalization is apical meristem.

Biodiversity loss occurs due to the reasons given below

$(i)$ Habitat loss and fragmentation

$(ii)$ Co-extinction

$(iii)$ Over-exploitation

$(iv)$ Alien species invasion

Identify the correct reasons

The most used domesticated animal by Eskimos is

Black rot of mustard is caused by