**Core Concept**
The assessment of pain in children requires a scale that is easy to understand and can accommodate their cognitive and linguistic abilities. The scale should be validated for use in children of different ages to ensure accurate measurement.

**Why the Correct Answer is Right**
The Faces Pain Scale-Revised (FPS-R) is a widely used tool for assessing pain in children as young as 3 years old. It consists of six facial expressions ranging from a happy face (no pain) to a very unhappy face (worst pain). Children are asked to point to the face that best represents their pain level. This scale is effective because it allows children to express their pain in a non-verbal way, making it more reliable and valid.

**Why Each Wrong Option is Incorrect**
**Option A:** The Wong-Baker Faces Pain Rating Scale is another valid tool, but it is more suitable for children aged 3-12 years. It is not as effective for 5-year-olds as the FPS-R.
**Option B:** The Visual Analog Scale (VAS) is a linear scale that is often used in adults but can be difficult for young children to understand.
**Option C:** The Numerical Rating Scale (NRS) is also commonly used in adults and can be challenging for young children to comprehend.

**Clinical Pearl / High-Yield Fact**
When using the FPS-R, it's essential to validate the child's pain assessment by asking them to point to the face that represents their pain level. This helps to ensure that the child understands the scale and can accurately express their pain.

**Correct Answer: C. Visual Analog Scale (VAS) is not the best option for a 5-year-old child.