**Question:** Z-value of an organism:

A. 0.5
B. 1
C. 2
D. 3

**Core Concept:**
The Z-value represents the number of standard deviations an observed value falls from the mean of a particular characteristic within a population. In other words, it measures the degree to which an individual is different from the average of a trait in a population. High Z-values (either positive or negative) indicate a significant deviation from the mean, while low Z-values (close to zero) suggest minimal deviation.

**Why the Correct Answer is Right:**
The correct answer is **D. 3**. Z-values are typically categorized into four groups based on their magnitudes:

1. Z-value < -3: Very low 2. -3 ≤ Z-value < 1: Low 3. 1 ≤ Z-value < 3: Moderate 4. Z-value ≥ 3: High In the context of this question, the term "Z-value" is referring to the degree of abnormality of a trait value relative to the mean in a population. A Z-value of 3 indicates a high degree of abnormality, which is why option D is correct. **Why Each Wrong Option is Incorrect:** A. 0.5: This is too low to represent a high degree of deviation from the mean. B. 1: This is too low to signify a high degree of deviation from the mean. C. 2: This is too low to represent a high degree of deviation from the mean. **Clinical Pearl:** Understanding Z-values helps medical professionals interpret statistical data related to patient characteristics or treatment outcomes. For example, in clinical trials or epidemiological studies, Z-values can help determine if a measured characteristic or outcome is significantly different from a control group or if a treatment has a significant effect. It also helps determine the practical importance of the difference between two values. By knowing the magnitude of Z-values, medical professionals can assess the clinical significance of a characteristic or outcome and make appropriate decisions for patient care or research.