A、He was first of all a scientist. B、He was not only a naturalist but also a scientist. C、He was no more than a born naturalist.

Before World War n, we spent our summer holidays in Hungary. I have only the dim memory of the house we lived in, of my room and my toys. Nor do I recall clearly the large family of grandparents, aunts, uncles and cousins who gathered next door. But I do have a clear memory of the dogs, the farm animals, the local birds, and above all, the nature.
    I’m a naturalist, not a scientist. I have a strong love of the natural world and my enthusiasm has led me into varied investigations. I love discussing my favourite topics and enjoy burning the midnight oil while reading about other people’s observations and discoveries. Then something happens and brings these observations together in my conscious mind. Suddenly you fancy you see the answer to the riddle, because it all seems to fit together. This has resulted in my publishing 300 papers and books, which some might honor with the title of scientific research. But curiosity, a keen eye, a good memory and enjoyment of the animal and plant world do not make a scientist: one of the outstanding and essential qualities required is self-discipline, a quality I lack. A scientist requires not only self-discipline but hard training, determination and a goal. A scientist, up to a point, can be made. A naturalist is born. If you can combine the two, you get the best of both worlds.
Questions 23 to 25 are based on the passage you have just heard.
23. Why couldn’t the speaker remember his relatives clearly?
24. What can be inferred about the speaker from the passage?
25. Why did the speaker think he was a naturalist rather than a scientist?