Essential medicines are those medicines:
**Core Concept**
Essential medicines are a set of medicines that are considered necessary for a healthcare system to provide adequate care to its population. The World Health Organization (WHO) defines essential medicines as those that satisfy the health care needs of the majority of the population, and are available within the context of functioning health systems at all times.
**Why the Correct Answer is Right**
The correct answer refers to the definition of essential medicines as those that are safe, effective, and of high quality, while also being affordable and accessible to the population. This definition is based on the principle of ensuring that all individuals have access to necessary healthcare services, regardless of their socioeconomic status. Essential medicines are selected through a rigorous process, taking into account the prevalence of diseases, the availability of healthcare resources, and the health needs of the population.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the characteristics of essential medicines. While safety and efficacy are crucial, they are not the sole defining features of essential medicines.
**Option B:** This option is also incorrect because it focuses on the cost of medicines rather than their accessibility and availability. Essential medicines are not necessarily the cheapest options, but they are affordable and accessible to the population.
**Option C:** This option is incorrect because it refers to the process of selecting essential medicines, rather than their defining characteristics. Essential medicines are not just those that are selected through a process, but also those that meet specific criteria.
**Clinical Pearl / High-Yield Fact**
It's essential to note that essential medicines are not limited to a specific list of drugs, but rather a concept that guides healthcare policy and decision-making. The WHO updates the list of essential medicines periodically to reflect changes in disease prevalence, healthcare needs, and available treatments.
**Correct Answer: D. Essential medicines are those that are safe, effective, and of high quality, while also being affordable and accessible to the population.**