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.

Given Relationship: 'invade', Sentence: 'After the United States invaded Grenada in 1983 , the communist junta of Hudson Austin and Bernard Gourd was replaced by a government that allowed a free press and opposition parties to flourish .'
invaded

Given Relationship: 'be son of', Sentence: 'Mary Tyler married James Baldwin , son of John Baldwin and Hester Larkin , 20 January 1714/15 St Barnebas Church , Queen Anne Parish , Prince George 's Co , MD.'
son

Given Relationship: 'be form of', Sentence: 'Kamagra is a form of Generic Viagra , the cost-effective supplement in comparison to its brand equivalent .'

form