What is history of A Country's Sphere of Influence

Sphere of influence, in international politics, the claim by a state to exclusive or predominant control over a foreign area or territory. ...

Explanation:

roosevelt believed that in light of the country's recent military successes, it was unnecessary to use force to achieve foreign policy goals, so long as the military could threaten force. this belief, and his strategy of “speaking softly and carrying a big stick,” shaped much of roosevelt's foreign policy.

the structure was most likely used for;

c. playing a ball game with stone hoops