Final answer:
The best answer, based on modern psychological understanding, is 'd. conclusive,' but this reflects the nuances and evolving approach to gender dysphoria, rather than an unequivocal resolution toward one's biological sex.
Step-by-step explanation:
According to the information provided and current understanding within the psychological and medical communities, the answer to the question "According to the author, ______ studies have shown that therapy successfully helps an adult with gender dysphoria resolve with their biological sex." would be d. conclusive. However, it is important to note that the term "conclusive" in this context does not necessarily mean universally accepted or without ongoing debate. The field acknowledges a complex interplay between biology and culture in gender identity, and while studies have provided some insights, approaches to care are individualized and constantly evolving.
Furthermore, dysphoria treatment and understanding are subject to significant change and discussion as societal attitudes evolve and research continues. The DSM-5 has reclassified Gender Identity Disorder to Gender Dysphoria to reduce stigma, recognizing the condition without pathologizing the identities of those who experience it. Thus, the journey towards resolving gender dysphoria is not seen as aligning with one's biological sex per se, but rather involves aligning one's physical body and social expression with one's gender identity.