Question: which of the following helmiths feeds on blood
[{'answer': 'Necator americanus', 'provenance': [{'wikipedia_id': '971658', 'title': 'Helminthiasis', 'start_paragraph_id': 22, 'start_character': 98, 'end_paragraph_id': 22, 'end_character': 116, 'bleu_score': 1.0, 'section': 'Section::::Secondary effects.:Anemia.\n'}]}, {'answer': 'Ancylostoma duodenale', 'provenance': [{'wikipedia_id': '971658', 'title': 'Helminthiasis', 'start_paragraph_id': 22, 'start_character': 123, 'end_paragraph_id': 22, 'end_character': 144, 'bleu_score': 1.0, 'section': 'Section::::Secondary effects.:Anemia.\n'}]}, {'provenance': [{'wikipedia_id': '971658', 'title': 'Helminthiasis', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 0, 'bleu_score': 1.0, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12841793964120808116}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '971658', 'title': 'Helminthiasis', 'start_paragraph_id': 22, 'start_character': 0, 'end_paragraph_id': 22, 'end_character': 941, 'bleu_score': 0.939240878781403, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12841793964120808116}, 'section': 'Section::::Secondary effects.:Anemia.\n'}]}, {'provenance': [{'wikipedia_id': '971658', 'title': 'Helminthiasis', 'section': 'Section::::Secondary effects.:Anemia.\n', 'start_paragraph_id': 22, 'end_paragraph_id': 22, 'meta': {'evidence_span': ['bility to learn new information, and apathy, irritability, and fatigue. A study of the effect of deworming and iron supplementation in 47 students from the Democratic Republic of the Congo found that the intervention improved cognitive function. Another study found that in 159 Jamaican schoolchildren, deworming led to better auditory short-term memo', 'This is most severe in heavy hookworm infections, as "Necator americanus" and "Ancylostoma duodenale" feed directly on the blood of their hosts.', 'Helminths may cause iron-deficiency anemia. This is most severe in heavy hookworm infections, as "Necator americanus" and "Ancylostoma duodenale" feed directly on the blood of their hosts. Although the daily consumption of an individual worm (0.020.07 ml and 0.140.26 ml respectively) is small, the collective consumption under heavy infection can be clinically significantly. Intestinal whipworm may also cause anemia. Anemia has also been associated with reduced stamina for physical labor, a decline in the ability to learn new information, and apathy, irritability, and fatigue. A study of the effect of deworming and iron supplementation in 47 students from the Democratic Republic of the Congo found that the intervention improved cognitive function. Another study found that in 159 Jamaican schoolchildren, deworming led to better auditory short-term memory and scanning and retrieval of long-term memory over a period of nine-weeks.']}}]}]