Explain how hibernation and migration are responses to an external stimulus

To Explain this we have to look at How animals  and plants live in real life, For Example , a plant would hibernate in the winter , due to the cold , some plants go dormant ( dormant is when a animal or plants action slows down or stop. ) and the external stimulus would be the sun , warming the plant , the plant would still be alive, of course but it would be sort of in a sleep state , Now to answer your question on Migration and how it ties in with this , Lets look at another example for this one : Canadian geese  Fly south for the winter, correct?  well this is mostly due to the cold , Etc ... so when those geese get cold they leave , the External stimulus would be Wind ,temperature , etc ... :)

B. would complete your answer. give me brainliest!

The salt in the sea water dehydrated the sailor because her body could not take in the amount to salt in the sea water