Every year birds migrate searching for better environments to acquire food. As winter approaches, birds migrate to the South, looking for warmer places. However, climate changes can affect this behavior. Stead of flying from North to South, birds can find warm enough places flying on an East to West axis. They no longer need to go down to the South to find warmer places because they can find it in Europe, for example. So, it may change the migration, which starts to occur further East, considering that North America is located on the West (globaly speaking), looking for warmer places in the European continent, for example. Therefore, the correct answer is D: Flying further East.