What was the political relationship between the Kingdom of Kush and Egypt? Egypt and Kush were never truly independent.
The two nations competed for control over Nubia.
The two kingdoms had few links besides geography.
Kush and Egypt shared cultures and constantly worked together.

Correct answer is The two nations competed for control over Nubia.

Explanation:

First option is not correct as both countries were independent. Egypt had a lot of dynasties that ruled in the country.

Second option is correct as Kush created an independent country on the soil of Nubia and fought for control with Egypt. They even ruled in Egypt for some period.

Third option is not correct as they were trading a lot for example.

This is not correct as their cultures were quite different and were very often engaged in quarrels.

the border between arizona and new mexico is a thin, black line; this indicates a state boundary.

its correct: it's a thin line, and it's a state boundary, correct