In the absence of any information regarding the acquisition of share in profit of the retiring/deceased partner by the remaining partners, it is assumed that they will acquire his/her share in:

Old Profit Sharing Ratio

The correct answer is Option (4) → Old Profit Sharing Ratio

In the absence of any specific agreement or information regarding how the continuing partners acquire the retiring or deceased partner's share of profit, it is assumed that they will acquire that share in their Old Profit Sharing Ratio relative to each other.