The sentence that states the most reasonable inference and provides a valid clue to support it is:
Ernesto does not know how long he will stay in Tucson.
My mother and I were to go to another city called Tucson and wait there until another pass and money could be obtained.
Explanation:
An inference is a deduction you make in base of the information that you receive in a text, the line "My mother and I were to go to another city called Tucson and wait there until another pass and money could be obtained." shows the uncertainty of the situation and how they are not in a position where they can program their activities since they depend on others.
