Answer:
A. Many of the cliff dwellings are accessible only by rope ladder.
Step-by-step explanation:
According to the excerpt, archeologists believe that the Ancestral Pueblo people began building their homes in cliffs to defend themselves in times of war.
The evidence from the text that supports this conclusion is that many of the cliff dwellings are accessible only by rope ladder.
This is because, by showing that the Pueblo people had been building their homes in the cliffs to protect themselves in times of war, he proves his point.