Which one of the following penicillin group drug is penicillinase resistant?

Cloxacillin is a penicillinase resistant penicillin. It has an isoxazole side chain that protect beta lactam ring from the attack of staphylococcal penicillinase. It is also acid resistant. It is more active than methicillin against penicillinase producing staphylococci, but not against MRSA. Cloxacillin is incompletely absorbed from oral route, it is >90% plasma protein bound. It is metabolized by the liver and is eliminated primarily by the kidney. Ref: Essentials of Medical Pharmacology, 5th Edition, Pages 659-661