Nafcillin oxacillin methicillin dicloxacillin

Which of the following molecular structures makes the antibiotics nafcillin, oxacillin, methicillin, and dicloxacillin resistant to cleavage by bacterial beta-lactamases?

1: Beta-lactam ring
2: Bulky R group
3: Peptidyl side chain capped with a saturated alkyl tail
4: Sulfonyl group connected to an amine group