Which of the following statements with regard to large stock dividends is true?

a$.$ As a result of the stock dividend, retained earnings is reduced by the par value of the stock issued.

b$.$ Retained earnings is reduced by the market value of the stock issued in the stock dividend.

c$.$ If the market price of the stock before a $50\%$ stock dividend is $$30,$ after the stock dividend it will be $$45.$

d$.$ As the result of a $50\%$ stock dividend, a stockholder who had previously held $20$ shares will then hold $40$

shares.