57.
The answer is: B
Explanation
The correct option is B: a third party.
According to Section 44(e) of the Indian Partnership Act, 1932, one of the grounds for dissolution by the court is that a partner, other than the partner suing, has in any way transferred the whole of his interest in the firm to a third party. This means that the partner has given up his rights and obligations as a partner to someone outside the firm, which may affect the continuity and stability of the partnership.
Therefore, the remaining partners can seek dissolution of the firm on this ground.