Self-esteem is best defined as:

Self-esteem is fundamentally about how individuals perceive and evaluate themselves, which encompasses both their self-worth and self-acceptance. This definition is correct because self-esteem reflects an individual's overall appraisal of their own value or worthiness, which can be influenced by various experiences, beliefs, and social interactions. It involves both positive and negative feelings about oneself, depending on personal experiences, external feedback, and internal reflections.

In contrast, the other definitions do not capture the essence of self-esteem. Labeling oneself (as mentioned in option A) can influence behavior but does not inherently convey valuation or worth. Comparing oneself with others (as indicated in option B) can relate to self-esteem but is more about a social process than the evaluation of worth itself. Lastly, relating self-esteem strictly to academic achievement (as seen in option D) is too narrow; self-esteem encompasses a broader range of life aspects and is not confined to academic performance. Thus, the definition focusing on evaluation of one's worth encapsulates the concept of self-esteem most accurately.