A healthcare professional is caring for a client receiving gentamicin therapy. Which of the following client assessments is a priority for the healthcare professional to monitor for an adverse effect of this medication?

The correct answer is D: Hearing acuity. Gentamicin is known to be ototoxic, which means it can cause damage to the auditory system leading to hearing loss. Monitoring hearing acuity is crucial to detect early signs of hearing impairment. Monitoring urinary output (choice A) is important for assessing kidney function but is not directly related to gentamicin's adverse effects. Monitoring serum glucose (choice B) and respiratory rate (choice C) are not specifically associated with gentamicin therapy.