What factor increases a geriatric patient's risk of medication errors?

Polypharmacy is the correct choice because it refers to the concurrent use of multiple medications by a patient, which is especially common among geriatric patients due to the prevalence of multiple chronic conditions requiring different treatments. The complexities involved with taking several medications can lead to confusion regarding dosages, timing, and potential interactions between the different drugs. This increased burden can heighten the chances of medication errors, such as taking incorrect doses, forgetting a dose, or mixing up medications.

Additionally, the cognitive changes that can accompany aging, such as memory impairment or diminished understanding of instructions, can compound the risks associated with polypharmacy. Therefore, the more medications an older adult is prescribed, the greater the likelihood of experiencing medication errors, making polypharmacy a significant factor in this context.