Foreign propagandists have a strange misconception of our national character. They believe

that we Americans must be hybrid, mongrel, undynamic; and we are called so by the enemies of democracy because, they say, so many races have been fused together in our national life. They believe we are disunited and defenseless because we argue with each other, because we engage in political campaigns, because we recognize the sacred right of the minority to disagree with the majority and to express that disagreement even loudly. It is the very mingling of races, dedicated to common ideals, which creates and recreates our vitality. In every representative American meeting there will be people with names like Jackson and Lincoln and Isaacs and Sehultz and Kovack and Sartori and Jones and Smith. These Americans with varied backgrounds are all immigrants or the descendants of immigrants. All of them are inheritors of the same stalwart tradition of unusual enterprise, of adventurousness, of courage--courage to "pull up stakes and git moving". That has been the great compelling force in our history. Our continent, our hemisphere, has been populated by people who wanted a life better than the life they had previously known. They were willing to undergo all conceivable hardships to achieve the better life. They were animated, just as we are animated today, by this compelling force. It is what makes us Americans.

The title below that best expresses the main idea of this selection is ______.

A．No Common Ideals

B．America's Motivating Force

C．American Immigrants

D．The Evils of Foreign Propaganda