20273
Estrogen receptor ( ER ) antagonists are generally thought to inhibit estrogen action through competitive inhibition , resulting in receptor binding to antagonist rather than agonist .
 Chemical: Estrogen; Chemical: estrogen
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: Estrogen, estrogen 
Answer:
 Chemical: Estrogen; Chemical: estrogen