The answer is B. the United States.
The line is "I pledge allegiance to the flag of the Unites States of America."
That is because the Czar knew that fighting the Austria-Hungary empire and Germany was inevitable and war was brewing. Of course, Russians did not see the end of the war due to the Bolshevik revolution that had them retreat from the war and cease their participation and overthrowing the king.
The American colonists were driven to declare war on the British Empire, because they were being oppressed, and not treated as citizens. They believed that the British had no right to impose more taxes on them, and so declared independence
hope this helps
