According to Boyle's law, as the volume of a container decreases.

A. It causes extreme depression of the respiratory rate: CO binds hemoglobin and impairs O₂ delivery; respiratory depression is not the primary danger
B. It drastically decreases the pH of the blood: CO poisoning does not primarily cause a dramatic blood pH drop
C. It binds to the oxygen-binding site on hemoglobin, so the O₂-carrying ability of the blood is reduced: CO binds avidly to hemoglobin’s heme sites, displacing O₂ and reducing oxygen carriage and delivery
D. It triggers hyperventilation, causing a severe drop in PCO₂ and increase in blood pH: Hyperventilation is not the main mechanism of CO toxicity

A. Diapedesis (transmigration): the cell is shown squeezing through the vessel wall (leaving the bloodstream), which is diapedesis (also called extravasation).
B. Phagocytosis: phagocytosis is ingestion of particles/pathogens by a phagocyte; the image shows movement out of a vessel, not engulfment of material.
C. Chemotaxis: Incorrect (related but not the pictured action) -chemotaxis is directed movement toward chemical signals; a leukocyte may chemotax once in the tissue, but the image specifically shows the mechanical passage through the endothelium (diapedesis).
D. Margination/Rolling: margination/rolling are earlier steps along the endothelium where leukocytes slow and adhere; the image shows a cell already squeezing through the wall, which is the next step (diapedesis).