You are on the scene of a​ 50-year-old male who lacerated his arm on a sheet of plate glass. He is​ pale, diaphoretic, and mumbling incoherently. You have controlled an arterial bleed with direct pressure. His blood pressure is​ 70/40, pulse​ 120, and respiratory rate of 28. Which of the following signs is the most​ concerning?
A. Altered mental status
B. Tachycardia
C. Blood pressure
D. Respiratory rate