Detailed Instructions: From the given sentence, extract the phrase (often noun or verb) that carries the given relationship. The generated phrase should be present in the sentence.
Q: Given Relationship: 'be son of', Sentence: 'In 1706 , one-half interest was sold to John Watson , and in 1716 , Mr. Watson and James Warren , son of Nathaniel , sold to John Cushman .'
A:
son