According to the California state law, a developmental disability:

The correct choice highlights the definition of a developmental disability as outlined by California state law, which specifies that such disabilities significantly impair an individual's ability to perform three or more major life activities. These major activities could include things like self-care, learning, communication, mobility, and social interactions. By focusing on the significant limitations in these areas, the law emphasizes the impact of developmental disabilities on daily living and overall functioning.

The other choices do not accurately capture the nature of developmental disabilities. For instance, stating that it always begins before someone is born implies a causation that isn't universally applicable to all developmental disabilities, as some may manifest later due to various factors. The notion that developmental disabilities can simply go away through medication and therapy is misleading, as these interventions may help manage symptoms but do not cure the underlying disability. Furthermore, stating that developmental disabilities only include physical challenges ignores the broad spectrum of cognitive, emotional, and social disabilities that can fall under this classification. Thus, the emphasis on significant limitations across multiple major activities captures the true essence of what constitutes a developmental disability according to the law.