9393
Magnesium is required as a cofactor although some activity is observed with ferrous ions .
 Chemical: Magnesium; Chemical: ferrous
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: Magnesium, ferrous 
Answer:
 Chemical: Magnesium; Chemical: ferrous