On the admission of a partner, increase in the value of asset is debited to :

Asset A/c

The correct answer is option (2) : Asset A/c

When a new partner is admitted, the assets and liabilities of the existing firm are revalued to reflect their current market value. The journal entry for the increase in value of asset is as follows-
Asset A/c Dr.
    To Revaluation A/c
(Increase in value of asset recorded)

Debiting the Asset Account: The increased value of the asset is debited to the specific asset account (e.g., Land Account, Machinery Account, etc.) as amount of asset is increased and increase in asset is debited to specific asset account.
Crediting the Revaluation Account: The corresponding increase in value of asset is credited to the Revaluation Account as it is a gain for the firm and revaluation account has nominal nature which has the rule of ' debiting all expense & loss and crediting all income & gain'.

Therefore, the increase in the value of an asset is not directly debited to Profit and Loss Adjustment A/c, Old Partners Capital A/c, or the Profit and Loss Account.