the right answer is actually C. Jagron
The predicate nominative is B. fish because it follows the word 'is' and can be switched with the subject (a seahorse IS a fish)
"First", you take out some gram crackers. "Next", you spread some peanut butter on top. "finally", you can add a dash of cinnamon.
you can go a little bit more into detail on yours and make it longer, but this is just a little example.