Eli Whitney is best known for inventing which device?

• A. The cotton gin
• B. The spinning jenny
• C. The telegraph
• D. The steam engine

Answer: (A)

The main idea here is recognizing a landmark invention that transformed US agriculture and industry. Eli Whitney is best known for the cotton gin, a machine that quickly and efficiently separates cotton fibers from seeds. Before the gin, this task was extremely labor-intensive, so the invention dramatically increased how much cotton could be processed in a day.

Patented in 1794, the cotton gin made cotton a highly profitable crop in the Southern states, helping to drive a massive expansion of cotton plantations. That economic shift also strengthened the reliance on enslaved labor to grow, pick, and process the cotton, shaping social and political realities in the era.

Other options were created by different inventors or in different contexts—the spinning jenny by James Hargreaves, the telegraph by Samuel Morse, and the steam engine developed over time by various contributors. The cotton gin is the invention most closely associated with Whitney and the one that had the lasting impact most people remember.