Step 1: Understanding the concept of rebirth.
The concept of rebirth, or samsara, is a central belief in Hinduism. According to Hindu philosophy, after death, the soul is reborn into another body, and this cycle continues until the soul attains liberation (moksha).
Step 2: Identifying other religions.
While other religions like Buddhism also believe in reincarnation, the question specifically asks about the religion most associated with the concept of rebirth. Hinduism is the primary religion where this belief is fundamental.
Step 3: Conclusion.
The concept of rebirth is most prominently associated with Hinduism.
Final Answer: \[ \boxed{\text{The correct answer is (A) Hindu.}} \]