The concept being referred to in this question is the adjustment of expenditure of capital nature to determine the actual deficit in the revenue account.

Option 1: Revenue deficit refers to the excess of revenue expenditure over revenue receipts. It does not specifically account for the adjustment of capital expenditure. This option can be eliminated.

Option 2: Effective revenue deficit is the correct answer. It takes into account the revenue deficit and adjusts it for the expenditure of capital nature. This concept provides a more accurate measure of the deficit in the revenue account.

Option 3: Fiscal deficit is the excess of total expenditure over total receipts. While it includes both revenue and capital items, it does not specifically focus on adjusting for capital expenditure. This option can be eliminated.

Option 4: Primary deficit refers to the fiscal deficit reduced by interest payments. It does not directly consider the adjustment of capital expenditure in the revenue account. This option can be eliminated.

In conclusion, the correct term for adjusting for capital expenditure in the revenue account is the effective revenue deficit, as mentioned in option 2.