The survival of nerve cells, as well as their performance of some specialized functions, is regulated by chemicals known as neurotrophic factors, which are produced in the bodies of animals, including humans. Rita Levi-Montalcini’s discovery in the 1950s of the first of these agents, a hormonelike substance now known as NGF, was led to Levi-Montalcini sharing the Nobel Prize for medicine in 1986.
In the mid-1940s, Levi-Montalcini had begun by hypothesizing that many of the immature nerve cells produced in the development of an organism are normally programmed to die. In order to confirm this theory, she conducted research that in 1949 found that, when embryos are in the process of forming their nervous systems, responsible for the effects Levi-Montalcini had observed: a protein that she named “nerve growth factor” (NGF).
NGF was the first of many cell-growth factors to be found in the bodies of animals. Through Levi-Montalcini’s work and other subsequent research, it has been determined that this substance is present in many tissues and biological fluids, and that it is especially concentrated in some organs. In developing organisms, nerve cells brain and spinal cord—die if the factor is not present or if they encounter anti-NGF antibodies.
What this question is testing
Your task
Pin down exactly what the question asks about the passage — a detail, the author's view, the structure, or the main point — before looking at the choices.
Common trap
Answers that restate a true detail from the passage but don't answer the specific question being asked.
Winning move
Anticipate the answer in your own words from the passage, then find the choice that matches that prediction.
Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.