She has always excelled ____ foreign languages. Choose appropriate preposition to complete the sentence-

• Excel in: 
English Meaning - To be very good at doing something. 
Bengali Meaning - দক্ষ। 

• Excel (in/at something)- She has always excelled in foreign languages.
- As a child he excelled at music and art.

• Excel (at doing something) - The team excels at turning defense into attack.

তাই এখানে সঠিক preposition টি হচ্ছে - 'in'. 

Source:
1. Advanced Learner's English Grammar & Composition by Chowdhury & Hossain.
2. Oxford Dictionary.