The correct option is C permanent
The word 'provisional' refers to something arranged for the present, possibly to be changed later.
Option A, unconditional refers to not being subject to any conditions.
Option B, abiding refers to lasting a long time.
Option C, permanent refers to lasting or intended to last or remain unchanged indefinitely.
Option D, lasting refers to be enduring or able to endure over a long period of time.
Thus, according to the meaning, the word 'permanent' is the opposite of the word 'provisional'.