Which element is most important for helping eyesight?
Se
S
As
Pu
Po
I found this on the web. I don't now how reliable it is so check it out with yout text and class notes. I also found reference to Mn being important but that isn't in your list from which to choose. I would not think Pu nor Po would be particularly important. In fact, Pu and Po are radioactive and PROBABLY would not be healthy.
http://www.google.com/search?hl=en&ie=ISO-8859-1&q=selenium+eyesight&btnG=Search
the answer is Se