What does the "O" line represent on the chart? What is indicated by a sharp spike below the “O” line?

During world war ii who is the commander-in-chief of the pacific fleet

Which source would best a historian understand the effect of the great chicago fire on families? a. a biography of a chicago family displaced by the fire b. a letter from a grandmother in new york to her family in chicago c. a newspaper editorial about families who were displaced d. an oral history dictated by an adolescent who fled the fire

Which is the correct description of a revolution and one of its outcomes