Why should piperacillin–tazobactam and gentamicin not be administered in the same IV solution?

Correct option is B

β-lactam antibiotics (like piperacillin) can chemically inactivate aminoglycosides (gentamicin) if mixed, reducing gentamicin’s efficacy. They should be given separately.
Explanation of options: (a) ✘ Nephrotoxicity risk exists, but main issue is inactivation. (b) ✔ Correct; chemical inactivation decreases gentamicin activity. (c) ✘ Precipitation isn’t the issue, inactivation is. (d) ✘ Resistance mechanism is unrelated.