What will be the new share of a remaining partner in the partnership firm after the retirement of a partner?

Old share + acquired share

The correct answer is option 3- Old share + acquired share

The retirement of  a partner leads to increase of share in profits of the remaining partners. The continuing partners may acquire the share of profits of the retiring/deceased partner according to their agreement. Thus,

New share of Continuing Partner = Old Share + Acquired share from the Outgoing Partner.