What is the answer and why? Can you also please explain why other answers are not suitable; and in the option 'D)' what does "without the others concern" means? Does it mean that the others did not give their consent on that, or what?

6. Michael and Jane are partners in international digital, a computer and digital product seller and distributer. It sells computers and digital gadgets. Dissolution of this partnership may be caused only by: A) Only by Michael and Jane expressly agree to dissolve the partnership. B) only by Michael selling her interest in the firm/partnership to Sam without Jane's consent. C) only by Jane adding Sam as a new partner without Michael's constant. D) by the partners agreeing to dissolve their firm/partnership, or by one partner, without the others concerned, selling his/her interest to a third party or adding another partner