Read the opening lines of Eleanor Roosevelt's speech "The Struggle for Human Rights."

I have come this evening to talk with you on one of the greatest issues of our time—that is the preservation of human freedom. I have chosen to discuss it here in France, at the Sorbonne, because here in this soil the roots of human freedom have long ago struck deep and here they have been richly nourished.

What tone do these lines convey?

A. a formal and serious tone
B. a conversational and inquisitive tone
C. a dissatisfied and pessimistic tone
D. an informal and indifferent tone