Question: what major desert encompasses most of northern africa
[{'answer': 'the Sahara desert', 'provenance': [{'wikipedia_id': '21714', 'title': 'North Africa', 'start_paragraph_id': 7, 'start_character': 49, 'end_paragraph_id': 7, 'end_character': 66, 'bleu_score': 1.0, 'section': 'Section::::Geography.\n'}]}, {'provenance': [{'wikipedia_id': '21714', 'title': 'North Africa', 'start_paragraph_id': 7, 'start_character': 47, 'end_paragraph_id': 7, 'end_character': 488, 'bleu_score': 0.6341731128493571, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3647267244831306243}, 'section': 'Section::::Geography.\n'}]}]