You Have Been Called to a New Year's Party for a Male

You have been called to a New Year's party for a male patient who was stabbed in the anterior chest. According to partygoers, the patient went outside with another male and was stabbed. Fifteen minutes later, he was found in the snow and 911 was called. When assessing this patient, what finding would you consider most serious and warrant immediate attention?

A) Complaint of a worsening headache
B) Capillary refill of 3 seconds
C) Decreased breath sounds to the left lung
D) Pain and bruising to the left thigh