Hi,

Of course, you will write the optional paper of Bengali Literature in bangla lanaguage only, this holds true for even other aspirants going for regional language as per their preference, for example if someone chooses Marathi then he or she needs to write the paper in that language only,

You can write the general studies paper in English and the optionals paper in bengali if you choose bengali literature, there are two optional papers of 250 marks each, all the languages included in the optional paper are part of eight schedule of the constitution, and apart from this there are also two language papers which are qualifying by nature.

As per the rule of Union Public Service Commission you can write the following papers in Bengali language

1. Any Modern Indian Language paper
2. Paper-i - Essay
3. Paper-ii - General Studies-I
4. Paper-iii - General Studies-II
5. Paper-iv - General Studies-III
6. Paper-v - General Studies-IV
7. Optional - Paper-I & Paper-II

Hope this helps.