There is not sufficient information to fill the two blanks after reading the first sentence. Two possible pairs of choices seem to make sense. In order select accurately, we read the second sentence in the paragraph. We are told that Mozart's genius is not the "blessing of the type conferred on a select few", but is the result of thousands of hours of grueling practice. The emphasis on "thousands" and "practice", which are contrasted against "divine blessing" suggests something that is methodical or measurable. Therefore, quantifiable is the best choice for the second blank. It makes sense to say "a series of readily quantifiable factors" but not "a series of readily intrusive factors" or "a series of readily pervasive factors", because there are no clues to suggest the factors are intrusive or pervasive.

Now coming to the first blank. We need a phrase that will describe how innate talent can be rendered as a series of readily quantifiable factors. Since Mozart's genius is quantifiable because of the thousands of hours of practice, we cannot call it a misattribution, so we can eliminate misattributed to. Now we have to choose between measured by and reduced to. The word "conveniently" before the blank and the later phrase "simply the result of" suggests breaking down a complex idea to its constituent parts, therefore, reduced to is the best choice, even though measured by is tempting given "quantifiable factors".