Which of the following was a cause of the French and Indian War?

a) Britain and France disputed borders in the Ohio River Valley.

b) French and American smugglers competed for navigation rights on the Ohio River.

c) France and Native Americans disputed trading rights in the Ohio River Valley.

d) Native Americans attacked British forts in the Ohio River Valley.

a) Britain and France disputed borders in the Ohio River Valley.

The correct answer is a) Britain and France disputed borders in the Ohio River Valley.

The correct answer is option a) Britain and France disputed borders in the Ohio River Valley.

To determine the cause of the French and Indian War, you can analyze the options provided and eliminate the ones that do not align with historical facts. Let's go through each option:

a) Britain and France disputed borders in the Ohio River Valley.
This option is correct and accurately represents one of the main causes of the French and Indian War. The conflict between Britain and France over territorial claims in the Ohio River Valley was a significant factor that led to the outbreak of the war.

b) French and American smugglers competed for navigation rights on the Ohio River.
While there may have been disputes over navigation rights, this particular factor was not a primary cause of the French and Indian War. It does not address the involvement of Native Americans, which was a significant aspect of the conflict.

c) France and Native Americans disputed trading rights in the Ohio River Valley.
Although Native Americans did play a role in the French and Indian War, there is no evidence to suggest that France and Native Americans specifically disputed trading rights as a cause of the conflict. This option can be eliminated as an incorrect answer.

d) Native Americans attacked British forts in the Ohio River Valley.
Native American attacks on British forts did occur during the French and Indian War, but they were not the main cause of the conflict. This option only represents a consequence or a consequence rather than a cause.

Therefore, by process of elimination, the correct answer is option a) Britain and France disputed borders in the Ohio River Valley.