Explanation: Lincoln’s address, known as the Gettysburg Address, emphasizes the significance of the soldiers’ sacrifices and urges the living to continue the work of preserving the nation and its freedom. It does not focus on comforting troops (A), as it addresses a broader audience at a cemetery dedication; nor does it announce specific plans to end slavery (C), though freedom is mentioned; nor does it celebrate a final victory (D), as the Civil War was ongoing. Instead, Lincoln clarifies the war’s purpose—preserving the Union and ensuring freedom—motivating continued dedication to that cause.

Explanation: Influenza is caused by influenza viruses (family Orthomyxoviridae). Bacteria, fungi, and protozoa can cause other types of infections, but the flu is specifically a viral disease.

Explanation: Langston Hughes was a central figure of the Harlem Renaissance—a flourishing of Black art and literature in northern cities driven largely by the Great Migration of African Americans out of the rural South. An article on how economic migration spurred an artistic revival directly illuminates the social and cultural forces that shaped Hughes’s work.

Explanation: The Renaissance—literally “rebirth”—marked a renewed interest in the literature, philosophy, and languages of ancient Greece and Rome. Scholars studied Latin and Greek texts and began writing serious works in their native tongues, breaking from the exclusively Church-centered medieval tradition.

Explanation: The area of a circle is given by A = πr². Given A = 314 ft², we approximate π ≈ 3.14, so r² ≈ 314 ÷ 3.14 ≈ 100, and r ≈ √100 = 10 feet. Choices B, C, and D yield areas far larger than 314 ft² when computed (e.g., r = 25 gives A ≈ 1962.5 ft²).