This is probably a stupid question, but as I was looking through the information available via the API, I realized that the movie object doesn't include a certification. For example, for the film The Substance rated R, the following aspects are recorded:

• adult
• backdrop_path
• genre_ids
• id
• original_language
• original_title
• overview
• popularity
• poster_path
• release_date
• title
• video
• vote_average
• vote_count

Is there any way I can find the rating for a film?