What is the meaning of the prefix "eu-"?

The prefix "eu-" is derived from the Greek word meaning "good," "well," or "normal." In medical terminology, it is commonly used to indicate a state of being or condition that is favorable or normal. For example, "euphoria" refers to a state of intense happiness and well-being, whereas "eutrophic" describes a nutrient-rich environment that supports healthy aquatic life. Thus, when "eu-" is chosen as the meaning of the prefix, it captures the essence of normalcy and positive condition effectively.

The other options do not align with this definition; "half," "different," and "excessive" represent distinct and unrelated concepts, making them unsuitable choices.