Answer:
B) George Washington was the first president of the United States
Step-by-step explanation:
This is because a predicate nominative or predicate noun completes a linking verb and renames/explains the subject like similar to a pronoun.
The verbs in A, B, and C have verbs followed by adjectives. Those descriptive words like delicious and beautiful even fun, aren't nouns. This leaves B as the only correct answer, the first president, renames the noun, like a pronoun.
Hope this helps.
From yours truly to you,
Que.