What is the best way to organize communication: article-category?

Question

Yii

I am using Yii2.
There is a model Article (article) and Category (category).
What is the best way to organize communication between them?
Options:
1. In the Article model, add the category_id field, where we enter the category ID.
2. Add an intermediate table articles_categories (category_id, article_id).
The advantage of the first option is the ease of working with categories and related articles.
Advantages of the second option: flexibility, no need to modify the Article when adding similar links (tags, authors, etc.), you can add several categories to one article.
I tend to the second option, but I want to hear your opinion.

Answer 1

Depends on TK. If the article can be in several categories - Many-Many. If guaranteed in one - One-Many.