Which isotope is appropriate for dating rocks that are billions of years old?

Uranium-238.

Uranium - 238' s half lif time is 4.5 billion years. This isotope decays until the stable isotope  Lead - 206.

It has been used to date the oldest rocks of the earth with a resulting age of approximately 4.0 billion years old.

The war began as a fight between mayans and the landowners of the country. the main causes of the guatemalan civil war was started by the greed of the united fruit company, the fear of communism, and the racism toward the  mayan  people.

Answer (b) they're often rural migrants with no title to housing or rights to established businesses