The correct option is B Because the new maritime code provides that even tiny islets can be the basis for claims to the fisheries and oil fields of large sea areas, it has already stimulated
The real subject of the sentence is 'the new maritime code'. However, only option B treats 'the new maritime code' as the main subject. Next, the use of the noun 'provision' and the verb 'provide' in the same sentence is illogical- this takes out option A (provisions that provide is inappropriate). In C, D and E there exist a misplaced modifier issue which makes the meaning of the sentences unclear - its unclear whether 'under' refers to the conditions of the maritime code or the sea area. Due to all these errors that options A, C, D and E commit but option B doesn't, B comes out as the correct answer.