How many parts does the declaration of independece have?

The system of checks and balances ensures that

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

What was the purpose of the u.s navy's convoy system