Question

the main, or central, idea of the passage is individuals with eidetic memory are temporarily able to retain detailed images in their minds. how does the detail in bold develop the main idea?
do some individuals have the amazing ability to take perfectly accurate, permanent mental \snapshots,\ which can be stored in the brain for future retrieval? fictional figures aside, no. but while this popular notion of \photographic memory\ is unfounded, research has demonstrated the existence of a fascinating phenomenon called eidetic memory, in which memory actually does have a camera - like quality. people with eidetic memory are able to look at an object or picture and then look away or close their eyes and continue to \see\ the object or picture in their minds. these images last only a few minutes at most before dissipating, and they are typically not entirely accurate. still, the degree of detail that \eidetikers\ can recall during those first few minutes is astonishing. interestingly, the phenomenon occurs almost entirely in children, with an estimated two to ten percent of children affected; virtually all eidetikers lose their unusual ability before reaching adulthood.
it shows that eidetic memory is of no value.
it highlights the limitations of eidetic memory.
it argues for the idea of true photographic memory.

Explanation:

The bolded detail "These images last only a few minutes at most before dissipating, and they are typically not entirely accurate" shows that eidetic memory has time - related and accuracy - related limitations. It does not say eidetic memory has no value (as it still has a high degree of detail in the short time). And it goes against the idea of true photographic memory (which is said to be unfounded in the passage).

Answer:

It highlights the limitations of eidetic memory.