This only serves their purposes.
1	This	this	PRON	DT	Number=Sing|PronType=Dem	3	nsubj	3:nsubj	_
2	only	only	ADV	RB	_	3	advmod	3:advmod	_
3	serves	serve	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	0	root	0:root	_
4	their	their	PRON	PRP$	Case=Gen|Number=Plur|Person=3|Poss=Yes|PronType=Prs	5	nmod:poss	5:nmod:poss	_
5	purposes	purpose	NOUN	NNS	Number=Plur	3	obj	3:obj	SpaceAfter=No
6	.	.	PUNCT	.	_	3	punct	3:punct	_
