During the admission of a new partner and the revaluation of assets and liabilities, several accounting entries and adjustments need to be made. The treatment of unrecorded assets and liabilities should follow specific accounting principles. In this context:

(1) Profit or Gain transferred to sacrificing partners: This is not directly related to the revaluation of assets and liabilities during the admission of a new partner.

(2) Reduction of liability should be credited to partners' capital accounts: This is a relevant step in the adjustment process to reflect the accurate value of the liabilities in the books.

(3) Unrecorded assets and liabilities should be written off immediately: This is a necessary step to ensure the accuracy and transparency of the financial statements during the admission process.

(4) Unrecorded Assets should be debited, and unrecorded liabilities should be credited to Revaluation A/c: This is a standard accounting practice to account for any unrecorded assets and liabilities during the revaluation process.

Based on the options provided, the most appropriate choice is (4) Unrecorded Assets should be debited, and unrecorded liabilities should be credited to the Revaluation A/c.