34819
Naturally occurring chromium is composed of three stable isotopes ; Cr , Cr and Cr , with Cr being the most abundant ( 83.789 % natural abundance ) .
 Cr, Cr, Cr, Cr
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Cr, Cr, Cr, Cr