4293
Among serotonin receptors , 5 - hydroxytryptamine 1B ( 5 - HT1B ) receptors have been associated with drug abuse including alcohol .
 Chemical: serotonin; Chemical: 5 - hydroxytryptamine; Chemical: alcohol
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: serotonin, 5 - hydroxytryptamine, alcohol 
Answer:
 Chemical: serotonin; Chemical: 5 - hydroxytryptamine; Chemical: alcohol