Answer:
Why are there no living cats on Mars?
I run through hills. I veer around mountains. I leap over rivers and crawl through the forests. Step out your door to find me. What am I?
I am an activity dogs are very good at when a ball is thrown.
In your fire you hear me scream creaking and whining yet I am dead before you lay me in your hearth.
Ripped from my ancestors home beaten and burned I become a bloodthirsty killer.
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.