Answer:
The correct answer is - option A. They evolved separately as they moved north and became two separate species
Step-by-step explanation:
Greenish warbler is a leaf warbler present in many regions in the world and shows migration in winters in the Indian region. The main region of the migration is Tibetan Plateau.
They migrated from the southern part of these birds range and moved north and evolved separately from the main species and become two distinct species due to their geolocation and environment change.