999
Eight rabbits were exposed to 0 . 7 + / - 0 . 4 mg / m3 Co2 + as CoCl2 and 1 . 2 + / - 0 . 7 mg / m3 Cr3 + as Cr ( NO3 ) 3 ( group Co + Cr ) , eight to 0 . 6 + / - 0 . 5 mg / m3 Co2 + ( group Co ) , and eight to filtered air ( control group ) , for 4 months , 5 days / week , and 6 hr / day .
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
 Entities:  
Answer:
 None