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
Which of the following is true about penicillin: 
Select and explain. 
A. Acid-resistant., B. Excreted mainly through the kidney., C. More concentrated in prostatic fluid., D. Is a broad-spectrum antibiotic.
B: Excreted mainly through the kidney.
Answer: B: Excreted mainly through the kidney. 
Explanation: None