8501
They set the maximum frequency at which the muscle can contract : The electrical activity of the GI tract can be subdivided into two categories : electrical control activity ( ECA ) and electrical response activity ( ERA ) .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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