Hello Aspirant,

As per the eligibility criteria for IFS exam released by UPSC, the candidate should have graduated in any of the following discipline :-

Animal Husbandry/Veterinary Science/Botany/Chemistry/Geology/Mathematics/Physics/Statistics and Zoology

Or

Should have bachelor's degree in Agriculture/Forestry/Engineering, but as you have mentioned that you have completed your graduation in Arts stream so you are not eligible for IFS exam. Also if you have studied Environmental science as a subject in BA then it doesn't means that you have graduated under any of the above discipline because your main stream of graduation is checked for eligibility.

You can check out the complete eligibility criteria from the link given below :-

https://competition.careers360.com/articles/ifs#IFS-Eligibility-Criteria-2020

I hope this information helps you.

Good Luck!!