Blood pressure decreases from arteries to veins; flow speed minimizes in capillaries Steps: - Recall blood pressure drops progressively: highest in aorta/arteries, lowest in large veins like vena cava. - Note flow speed is highest in large arteries, lowest in capillaries due to vast total cross-sectional area. - Match diagram points: assume 4 labels large vein (e.g., vena cava) for lowest pressure. - Assign 1 to capillaries for lowest speed, as total area expansion slows flow per continuity equation. Why D is correct: - Lowest pressure occurs in large veins (point 4) due to resistance losses; lowest speed in capillaries (point 1) via continuity equation (flow rate = area × velocity, large capillary area reduces velocity). Why the others are wrong: - A wrong: point 1 (capillaries) has low speed but moderate pressure; point 4 (veins) has low pressure but higher speed. - B wrong: point 2 (likely artery) has high pressure and speed; point 3 (small vein/arteriole) neither lowest. - C wrong: point 3 (small vessel) has neither lowest pressure nor speed; point 2 (artery) has high values. Final …