Can taking iron supplement during childhood prevent blindness true or false?

I believe it's false because the underlying cause of blindness is not only the absence of iron, it's like saying "If you consume carrots your eyesight will improve." Which isn't true because iron it's self isn't the main cause or blindness there can be many other ways which causes blindness like a disconnection in the brain.

Where are the options?

The correct answer is  "a) has ingredients that are high in nutrients."