Question: what category of elements is the most common in the periodic table
[{'answer': 'Main - group', 'provenance': [{'wikipedia_id': '19566', 'title': 'Main-group element', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 19, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '19566', 'title': 'Main-group element', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 206, 'bleu_score': 0.9402297675816911, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1929874097979804485}, 'section': 'Section::::Abstract.'}]}]