A sentence/a part of the sentence is underlined. Below are given alternatives to the underlined part which may improve the sentence. Choose the correct alternative. In case no improvement is needed choose No improvement.
The blue whale was thriving in all of the world's oceans until the turn of the century, at which time they became hunted to the point of extinction.
At the turn of the century, blue whales were thriving in all of the world's oceans
Blue whales were thriving in all of the world's oceans until the turn of the century
The blue whale was thriving in all of the world's oceans up until the turn of the century.
No improvement
B.
Blue whales were thriving in all of the world's oceans until the turn of the century