Answer:
The bolded words are a noun clause.
Step-by-step explanation:
A noun clause is a dependent clause that acts as a noun. Therefore, they can act as subjects, direct objects, indirect objects, predicate nominatives, or objects of a preposition. In this case, the noun clause acts as the subject of the sentence. You can identify the subject by asking the following question: What was obvious to all? The answer is the subject of the sentence, the clause "that she was unhappy".