16326
The food web structure and dolphins ' trophic level - specific consumption rates were evaluated using stable isotope ratios of carbon ( delta ( 13 ) C ) and nitrogen ( delta ( 15 ) N ) .
 carbon, ( 13 ) C, nitrogen, ( 15 ) N
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 carbon, ( 13 ) C, nitrogen, ( 15 ) N