Answer:
The best place to insert "who had no experience in the kitchen" is:
3. After "Eduardo" in the first sentence.
Step-by-step explanation:
The clause "who had no experience in the kitchen" has one purpose: to give more information about Eduardo. Therefore, the best place to put it is right when Eduardo is first mentioned, especially because that is the sentence which lets us know that Eduardo wants to learn how to cook. It makes sense that the two pieces of information should be given together: if he has no experience in the kitchen, nothing more natural than wanting to learn to cook.
Thus, the sentence becomes the following:
- Eduardo, who had no experience in the kitchen, wanted to learn how to cook, so he visited his friend Juan. Juan cooked while Eduardo watched and took careful notes.