The correct answer is - b. The whale populations are not rebounding as quickly as they might if all the countries agreed not to hunt whales.
Even though Japan and Norway are not large countries, they do have lot of area in the sea where they are whaling. Unfortunately, their waters are on the migratory routes of few species of whales, as well as some strictly living in those ares.
Despite all countries agreeing to not hunt whales, these two manage to make a lot of damage. Some species of whales have even gone extinct, while the other whales have troubles to rebound their population because of they are still hunted. Some whales though managed to rebound better, and the main reason for that is that Japan and Norway do not have access to the waters where they live.