Which of the following is not a mechanism for resistance to MRSA -
In the previous explanation, I have explained the mechanism of antibiotic resistance in general (for all staphylococci species).
Antibiotic resistance specific to MRSA:-

Mechanism of resistance of MRSA 

There are three known mechanisms for which Staphylococcus aureus become resistant to methicillin:-


Presence of penicillin-binding protein (PBP 2a) → Most cases
Modification of normal (intrinsic) penicillin-binding protein
Hyperproduction of beta-lactamase → rare


S. aureus strains have four intrinsic penicillin-binding proteins (PBPs) which have a high affinity for beta-lactam antibiotics.
PBP2a is an inducible acquired protein that is produced only by MRSA; it is not an intrinsic PBP.
PBP2a has a very low affinity for beta-lactam antibiotics → S.aureus strains containing PBP2a i.e.MRSA are resistant to all beta-lactam antibiotics


Production of PBP2a is chromosomally mediated. 
	Now see each option of question:


Resistance to MRSA is chromosomally mediated and involves the production of an altered penicillin-binding protein (PBP2a).
MRSA resistance is not absolutely beta-lactamase dependent. Though altered penicillin-binding protein is involved in most strains, rarely beta-lactamase production is also involved.
Intrinsic resistance is known, that means an alteration in intrinsic PBPs is also one of the mechanisms for resistance in MRSA. (reminding you PBP2a is not an intrinsic PBP, it is an acquired PBP).
Resistance is chromosomally mediated
Produced mainly by alteration in PBP's
MRSA resistance is absolutely beta lactamase dependent
Intrinsic resistance is known