Fred, a tennis coach, insists that he can make any reasonably healthy individual into an internationally competitive tennis player. Fred is echoing the thoughts of: A. Sigmund Freud. B. Iohn B. Watson. C. Abraham Maslow. D. William lames.

Let's briefly go over the main beliefs of the psychologists mentioned in the options: A. Sigmund Freud: Founder of psychoanalysis, Freud believed that behavior is driven by unconscious desires and motives, usually rooted in childhood experiences. B. John B. Watson: A major proponent of the school of thought known as behaviorism, Watson believed that behavior is the result of environmental influences and conditioning, and that humans can be shaped by controlling their environment. C. Abraham Maslow: Best known for his hierarchy of needs theory, Maslow proposed that humans have an innate drive to fulfill their potential and strive for self-actualization. D. William James: A philosopher and psychologist, he is known for his belief in pragmatism, meaning that the truth of an idea should be judged by its usefulness.

Based on the above information, we can deduce that the tennis coach's belief aligns most closely with the work of John B. Watson. Watson's belief that human behavior can be shaped by controlling their environment aligns with the tennis coach's idea that he can train anyone to become an internationally competitive tennis player. Therefore, the correct answer is: B. John B. Watson.