**Core Concept**
Penicillin G (PnG) is a narrow-spectrum beta-lactam antibiotic effective against Gram-positive bacteria, including those causing rat bite fever. Its pharmacokinetics and spectrum of activity are influenced by its chemical structure and mode of administration.

**Why the Correct Answer is Right**
Rat bite fever is a zoonotic infection caused by Streptobacillus moniliformis or Spirillum minus, both of which are susceptible to Penicillin G. The correct use of PnG in rat bite fever is supported by its efficacy against these Gram-negative bacteria and the absence of significant resistance. This is due to the bactericidal action of PnG, which inhibits cell wall synthesis by binding to penicillin-binding proteins (PBPs) on the bacterial cell wall.

**Why Each Wrong Option is Incorrect**
**Option A:** Penicillin G is not stable in the acidic environment of the stomach and is therefore not suitable for oral administration. It is typically given intravenously or intramuscularly to ensure optimal absorption and bioavailability.

**Option B:** Penicillin G has a narrow spectrum of activity, primarily effective against Gram-positive bacteria, and is not considered a broad-spectrum antibiotic like penicillin-resistant penicillins (e.g., ampicillin) or cephalosporins.

**Option D:** Probenecid actually increases the duration of action of Penicillin G by competitively inhibiting its renal tubular secretion, thereby reducing its clearance and increasing its plasma concentration. This is beneficial in maintaining effective tissue concentrations and preventing relapse.

**Clinical Pearl / High-Yield Fact**
When using Penicillin G, it's essential to consider the potential for allergic reactions, especially in patients with a history of penicillin allergy. Always assess the patient's medical history and perform necessary allergy testing before initiating treatment.

**✓ Correct Answer: C. Used for treatment rat bite fever**