13405
MATERIALS AND METHODS : Rats were presented with two levers , one of which delivered an immediate water reward on half of the trials , while the other lever delivered the same reward on every trial , but only after one of five increasing delays .
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities:  
Answer:
 None