Lo cual can only be used to refer to something that has already been mentioned in the same sentence.
Lo que can be used any time lo cual is used, and it can also be used to refer to something that has not been brought up before in the same sentence.
However the practice quiz at the bottom say
Lo cual is best for the sentence since it refers to an antecedent specifically mentioned earlier in the phrase
when i chose lo que as the answer as in the following example:
El niño gritó en voz alta, lo cual me molestó mucho.The child screamed in a loud voice, which upset me very much.
My question is, Should i adapt the definition? In which case the sentence above becomes,
El niño gritó en voz alta, lo que / lo cual me molestó mucho.
Or should I use lo cual over lo que whenever something is mentioned before