The correct answer is option 4, Corporation Tax. Constitution exclusively and totally assigns certain taxes to the Central Government, and Corporation Tax is one of them.

Let`s dissect the other options to understand why they are not correct:

Option 1, Estate Duty, is a tax on inherited property or assets. This tax is not exclusively assigned to the Central Government, as both the Central and State Governments have the power to levy it.

Option 2, Sales Tax, is a tax on the sale of goods and services. This tax is not exclusively assigned to the Central Government either, as both the Central and State Governments have the power to levy it.

Option 3, Taxes on Railway Fares and Freights, again, are not exclusively assigned to the Central Government. Both the Central and State Governments can levy these taxes.

Therefore, the exclusive and total assignment to the Central Government is only applicable to option 4, Corporation Tax.