The underlined part of sentence 1 is what kind of clause?

(1) that creatures living in the deep sea are in danger of starving to death
adverbial clause
adjectival clause
noun clause

The underlined part of sentence
 that creatures living in the deep sea are in danger of starving to death
 is 
adverbial clause
as
adverbial clause is dependent clause that function as an adverb and modifies a verb  so option 1 is correct
hope it helps

The answer is the father was relieved, the officer was tired.