Why did Princeps and his co-conspirators target Archduke Franz
Ferdinand?

Archduke was a target of assassination, because he was next in line to the throne, and was very wealthy. He was a target because many people in the Balkans were angered by Austria's annexation of Bosnia a few years earlier.

Explanation:

Hope this helps :)

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.