A patient with a history of cirrhosis presents with ecchymosis. Laboratory tests reveal prolonged prothrombin time (PT) and normal platelet count. What does the elevated PT most likely indicate in this patient?
a. Impaired hepatic synthesis of coagulation factors.
b. Vitamin K deficiency secondary to malabsorption.
c. Platelet dysfunction despite normal platelet count.
d. Increased hepatic synthesis of proteins C and S.