(E) is wrong because it is slightly too strong of a claim. The author is not claiming that the importance of motivation and interest shows that exceptional skill does not depend IN ANY WAY on the innate talents of individuals. Looking at the last sentence, the author makes a weaker claim: motivation and interest are better predictors than innate talent.
(A) is correct because after a superior performer undergoes extensive training, it's hard to tell whether they are superior performers because of their innate talent or because of their training. Lines 36-45 provide perhaps the best evidence for this, when the author discusses chess players without superior innate talent who can still perform very well because of training, perhaps as well as those with innate talent. Once a certain threshold is reached, it becomes difficult to differentiate those with talent from those who simply grinded enough. Hope this helps!