This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
When broad-spectrum antibiotics are administered with coumarin anticoagulants, the anticoagulant action may be: 
Select and explain. 
A. Reduced because of enhanced hepatic drug metabolism, B. Reduced because of increased protein-binding, C. Increased because of reduction of vitamin 'K' sources, D. Increased because of decreased renal excretion of the anticoagulant
C: Increased because of reduction of vitamin 'K' sources
Answer: C: Increased because of reduction of vitamin 'K' sources 
Explanation: None