instruction:
Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.
question:
Context: Biologists agree that the ancestor of mitochondria was an alpha-proteobacterium. But there is no consensus as to what constitutes an alpha-proteobacterial gene. Is it a gene found in all or several alpha-proteobacteria, or in only one? Here, we examine the proportion of alpha-proteobacterial genes in alpha-proteobacterial genomes by means of sequence comparisons. We find that each alpha-proteobacterium harbours a particular collection of genes and that, depending upon the lineage examined, between 97 and 33% are alpha-proteobacterial by the nearest-neighbour criterion. Our findings bear upon attempts to reconstruct the mitochondrial ancestor and upon inferences concerning the collection of genes that the mitochondrial ancestor possessed at the time that it became an endosymbiont. 
 Question: Which species of bacteria did the mitochondria originate from?
answer:
biologists agree that the ancestor of mitochondria was an alpha-proteobacterium.


question:
Context: Drowning Girl (also known as Secret Hearts or I Don't Care! I'd Rather Sink) is a 1963 painting in oil and synthetic polymer paint on canvas by Roy Lichtenstein. 
 Question: What material was used for Drowning Girl?
answer:
canvas


question:
Context: Krechek or krecek or sambal goreng krechek is a traditional Javanese cattle skin spicy stew dish from Yogyakarta and Central Java, Indonesia. 
 Question: The country of origin for Krechek is what?
answer:

indonesia