To be appointed as a member of the Finance Commission, a person needs to fulfill certain essential requirements. The correct answer is option 3, which states that the essential requirements include a person having wide experience in financial matters and administration, as well as a person having special knowledge of economics.

Let`s dissect each option for a better understanding:

- Option 1: States that the essential requirements include a Supreme Court judge or someone qualified to be appointed as such. While this may be a desirable qualification, it is not mentioned as an essential requirement for appointment as a member of the Finance Commission.

- Option 2: States that the essential requirements include a person having wide experience in financial matters and administration. This is indeed an essential requirement mentioned in the question.

- Option 3: States that the essential requirements include a person having special knowledge of economics. This is also an essential requirement mentioned in the question.

- Option 4: States that the essential requirements include a Supreme Court judge or someone qualified to be appointed as such, as well as a person having special knowledge of economics. This option combines two requirements mentioned separately in the question. However, it does not include the essential requirement of a person having wide experience in financial matters and administration.

Therefore, the correct answer to the question is