Concept:Shares given free to current shareholders based on how many shares they already own are called bonus shares.Explanation:When a company issues bonus shares, it does not ask existing shareholders to pay any money.These shares are distributed in proportion to the shares each shareholder already holds.This is often done to reward shareholders when the company cannot or does not want to pay a cash dividend.The other options are not correct: founders' shares, preference shares, and deferred shares all involve different rights or payments.Answer:D. bonus shares.