Question: NAME_1's thesis equates the concept of "computable function" with those functions computable by, for example, Turing machines. Which of the following is true of NAME_1's thesis?
A: It was first proven by NAME_2.
B: It has not yet been proven, but finding a proof is a subject of active research.
C: It can never be proven.
D: It is now in doubt because of the advent of parallel computers.
Please eliminate two incorrect options first, then think it step by step and choose the most proper one option. Provide two versions of response separated with exactly 6 asterisk symbols: ******.
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