Why do they (blood Banks) ask so many personal questions when I give blood

The highest priorities of the Blood Banks are the safety of the blood supply and our blood donors. Some individuals may be at risk of transferring communicable disease through blood donation due to exposure via travel or other activities or may encounter problems with blood donation due to their health. We ask these questions to ensure that it is safe for patients to receive your blood and to ensure that it is safe for you to donate blood that day.