This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
beta - Lactamases cause resistance to penicillins and cephalosporins by 
Select and explain. 
A. Breaking one chemical bond, B. Breaking two chemical bonds, C. Adding amino (NH2) groups to a molecule, D. Inhibiting transpeptidase enzymes
A: Breaking one chemical bond
Answer: A: Breaking one chemical bond 
Explanation: Penicillins and cephalosporins are called beta-Iactam drugs because of the importance of the intact BETA-lactam ring for antimicrobial activity. -Lac­tamases inactivate these drugs by breaking the single bond in their BETA-lactam ring. BETA-Lactamases are coded for by either a transferable plasmid or by the genome of the organism. Plasmids are extrachromosomal genetic elements that may be transferred among unrelated bacteria.