The correct answer is: Optional.
A partnership is a business relationship between two or more people who agree to share the profits and losses of the business. Under the Indian Partnership Act, 1932, registration of a partnership is not compulsory. However, there are certain benefits to registering a partnership, such as limited liability for the partners and the ability to sue and be sued in the name of the partnership.
Option A is incorrect because the Indian Partnership Act does not make registration of a partnership compulsory.
Option B is incorrect because the Income Tax Act does not make registration of a partnership compulsory. However, there are certain tax benefits available to registered partnerships.
Option C is incorrect because the Companies Act does not make registration of a partnership compulsory. Partnerships are not companies under the Companies Act.
Option D is correct because registration of a partnership is optional under the Indian Partnership Act.