答案：D

考查非谓语动词。如果把句子补充完整就不难看出：If they are given the right kind of training，可知主语they即these teenager soccer players与give之间是被动的关系，所以用过去分词。根据主、从句主语一致可省略从句主语的原则，连词if也可省，所以得出Given the right kind of training，these teenager soccer players...。