Question: which ruler fought the famous battle on the banks of jhelum river
[{'answer': 'Alexander the Great', 'provenance': [{'wikipedia_id': '720543', 'title': 'Battle of the Hydaspes', 'start_paragraph_id': 1, 'start_character': 56, 'end_paragraph_id': 1, 'end_character': 75, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'King Porus of the Paurava', 'provenance': [{'wikipedia_id': '720543', 'title': 'Battle of the Hydaspes', 'start_paragraph_id': 1, 'start_character': 80, 'end_paragraph_id': 1, 'end_character': 105, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '720543', 'title': 'Battle of the Hydaspes', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 456, 'bleu_score': 0.6991687621008451, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12704005266690753187}, 'section': 'Section::::Abstract.'}]}]