Hello,

You can write GRE/TOFEL/ IELTS. these are test which are done which makes sure that you can understand English and good at listening and speaking. English is a business language and works at every place.

You can go for any one you like. TOFEL and IELTS is bit easy then GRE. GRE also includes analytical skills. You have to practice and prepare so that you get a good score.

Hope it helps!