How do you rule out question choice (A)?

Hi there, I narrowed down the choices to answer choice (A) and (E) and selected answer choice (A). In the explanation of why answer choice (A) is incorrect, the following sentence is used: "Since interest isn't established as being related to the development of skills, this answer choice is out of scope" Using the logic of that explanation, one could apply that to answer choice (E) and argue that "Instruction" isn't established as being related to the development of skills, thereby being out of scope as well. After all, what if there is no "instruction" (let's assume we share a known, exact definition of the word 'instruction') and students happen to learn this subject simply by reading a book? It seems that you could argue that both answers are correct (By proposing alternative causes that challenge the assumption upon which the argument is built) and you could argue that both answers are incorrect (By noting that neither variable is established as being related to the development of skills). Can you please provide some differentiation between these two answers beyond what is given in the explanation for (A) being incorrect and (E) being correct? Thank you in advance, Jon