Hey There!!
I think the answer to this is: The 3 one is. A Relative. The 4 one is. A noun. And, The last one is. adverbial.
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Answer:
1. Titanic was difficult to locate in part because it was submerged in some of the world's deepest waters.
2. The Titanic was found in three locations in parts at a depth of 3840 meters (12,600 feet).
Explanation:
It laid unfound for 73 years because of the depth and different locations.