Pay attention in class, ask for help when you need it, stay out of trouble. That's what I do and I have A's is all classes except math which is a B. (sorry not trying to brag)
Your answer should be WHO.
Think of it like this: You wouldn't say "The boy it (a variant of 'which')", because it simply just sounds odd. Instead, you're wired to think "The boy, he (an unknown name, so it would be 'who')".
Explanation:
en el negocio se recomienda ser ingeniero
Answer: B!!
because it talks about nonliving things.
