What is the purpose of dr. heidegger’s experiment?

Which fact would this be, and how might you verify the truth?

Which impact did the civil war have on the spread of disease in texas a. disease decreased bc people left the area to fight in the war b. disease increased bc medicine was in short supply. c. disease increased bc many new diseases were brought to the area d. disease decreased bc confederate doctors distribute new medicines to local communities

What battle in the civil war was known as the bloodiest war ?