A New Partner may be admitted into a partnership:

With the consent of all old partners

The correct answer is option 2- With the consent of all old partners.

As per the Partnership Act, 1932, a new partner can be admitted into the firm with the consent of all the existing partners, unless otherwise agreed upon. With the admission of a new partner, there is a reconstitution of the partnership firm and all the partners get into a new agreement for carrying out the business of the firm.