The sentence speaks of the uncertainty generated by the subject of the sentence knowing that the third singular male person, obtained good grades even doing something that can be said contrary to the effort to obtain good grades.
We have the following options:
He proposes
He isolated
He performed
He relates
So, the most appropriate option would be "He isolated himself"
Thus, we have:
No sé cómo él se aisló en la escuela y sacó buenas notas.
Answer:
Option B
