Hi Pragya,
Although all the GRE subject tests hold weight in the eyes of the admissions committee, the two most viable subject tests which you could take to boost your chances for admission are the subject tests in:
Mathematics: https://www.ets.org/gre/subject/about/content/mathematics
Physics: https://www.ets.org/gre/subject/about/content/physics
Apart from the subject tests, the GRE General test is also a primary contributor to your application materials and selection process.
Dear Pragya,
If you want to study abroad, you need to prepare for GRE and IELTS. You can refer to the below mentioned links for details.
https://studyabroad.careers360.com/articles/gre
https://studyabroad.careers360.com/articles/ielts-test-pattern
Hope it helps.
Good Luck.
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