**Question:** Which of the following drugs develops the resistance by inactivating enzymes:

A. Penicillinase
B. Aminoglycosides
C. Cephalosporins
D. Fluoroquinolones

**Core Concept:** Developing drug resistance is a common phenomenon observed in microorganisms like bacteria. One mechanism of resistance involves the production of enzymes that inactivate the drug, making it ineffective.

**Why the Correct Answer is Right:** Penicillinase is an enzyme produced by some bacteria, specifically the producer of penicillin-resistant strains. This enzyme breaks down the beta-lactam ring of penicillin, rendering it unable to inhibit bacterial cell wall synthesis.

**Why Each Wrong Option is Incorrect:**

**Option B (Aminoglycosides):** Aminoglycosides are a class of antibiotics that inhibit bacterial protein synthesis. They do not develop resistance through enzyme inactivation. Instead, resistance occurs due to reduced permeability, active efflux pumps, or modification of ribosomal targets.

**Option C (Cephalosporins):** Similar to penicillin, cephalosporins also target bacterial cell wall synthesis. Resistance mechanisms include penicillinase production, reduced permeability, and beta-lactamase production which inactivates cephalosporins. However, cephalosporins are different from penicillin, and the correct answer should be Penicillinase.

**Option D (Fluoroquinolones):** Fluoroquinolones are a type of antibiotic that targets bacterial DNA gyrase and topoisomerase IV, enzymes involved in DNA replication and repair. Resistance to fluoroquinolones develops through various mechanisms such as mutations in the target enzyme, efflux pumps, and target modification. Inactivating enzymes are not the primary mode of resistance for fluoroquinolones.

**Core Concept:** Inactivating enzymes play a role in drug resistance, but the correct answer to this question should be Penicillinase (Option C), as it is the enzyme responsible for inactivating penicillin and related antibiotics.

**Why Each Wrong Option is Incorrect:**

**Option A:** Although Aminoglycosides are inactivated by enzyme production (aminoglycoside-modifying enzymes), they are not the correct answer to this question. The focus is on inactivating enzymes, and Penicillinase fits the criteria.

**Option C (Penicillinase):** Penicillinase is an enzyme produced by some bacteria that inactivates penicillin and related antibiotics, rendering them ineffective against the bacteria. This is the correct answer as it represents an enzyme that inactivates a class of drugs (beta-lactams) and fits the criteria of the question.

**Option D (Aminoglycoside-modifying enzymes):** As mentioned earlier, aminoglycoside modifying enzymes inactivate aminoglycoside antibiotics, not penicillin or penicillinase. This option is incorrect for the given question.

**Option E (Alteration of penicillin binding proteins):** This option describes a mechanism of resistance, where bacteria modify penicillin binding proteins, leading