Pretty sure it is C because it it divisible by 3. If you divide 15 you get 5 and if you divide 6 you get 2.
In General Wheelers own words, "this terrible catastrophe [sinking of the Maine] though not the cause of the outbreak of hostilities, certainly hastened the action of Congress in its declaration of war against Spain." According to Wheeler the Spains actions in Cuba were already leading to war between Spain and the US. The sinking of the Maine was the final straw that decided the congress to vote for war. But war would have come without the sinking of the Maine.
These brought about the time known as Prohibition. Liquor was illegal. A subculture would grow out it. The rise of speakeasies, moonshiners, rum runners, and the mob. The time of the gangster would evolve as they would use the illegal businesses to funnel cash and make themselves rich. Men like Babyface, Al Capone, and John Dillenger would rise to both fame and infamy.