Answer Only One Question

Lincoln was the 16th president of USA.

In a test when he was an elementary school student,the teacher told him: "you have two choices. 1. answer one difficult question, or 2. answer two easy questions."

Lincoln said with confidence: "I'll take the difficult question".

"Where do the eggs come from?"
"chicken."
"Then, where do the chicken come from?"
"Sir, this is the second question."