Read the following paragraph from the article.

On October 9, 1943, she married Louie, whom she called "Cliff," by then a major in the Chinese air force. "KNOT TIED TODAY," she wrote in a telegram to another pilot. "CAVU FOR CLIFF AND ME." CAVU, an acronym used by pilots, stands for "ceiling and visibility unlimited."

Which word from the paragraph shows an optimistic tone?