What was the famous and important line from president kennedy’s speech?

“tear down this wall.”
"my fellow americans: ask not what your country can do for you — ask what you can do for your country."
"ich bin ein berliner."
“i appreciate my interpreter translating my german.”

My fellow Americans; ask not what your country can do for you -- ask what you can do for your country.

Explanation:

John F. Kennedy was the United States President from 1961 until his assassination on 1963, and is one of the most iconic presidents of the United States, with his inaugural address being considered one of the greatest speeches of all time. He addressed to more than 200,000 people during his inaugural ceremony (it was the first transmitted in color T.V.) and told them to gather together and embrace their country, to act through ethics and take a stand to defend liberty and peace against communism, war and poverty. One of the most famous parts of his speech is "ask not what your country can do for you, ask what you can do for your country".