The central idea of the text is that the researchers used improved gene-editing techniques to repair a mutated gene that caused a genetic disease, as shown in option D.
The central idea of the text must be planned before the text is written, as it will direct the author to present evidence, build arguments and organize the textual structure to highlight it.
This question is about the article "Tuesday-Molecular scissors fix disease-causing flaw in human embryos."
In the link, you can find more information about the central idea:
https://brainly.com/question/1914191