How do salmon travel to get back to where they were hatched?

When they find the river they came from, they start to use smell as a navigator to find their way back to their home stream. They develop this ability ("smell memory bank") when they start migrating to the ocena as young fish.

Scientists believe that salmon navigate by using the earth's magnetic field like a compass. When they find the river they came from, they start using smell to find their way back to their home stream. They build their 'smell memory-bank' when they start migrating to the ocean as young fish.

I believe it's D. Neither the busses nor the train brings us to the stadium.