please explain.

29. John Owns 12,000 shares of Do it Write, Inc. The shares are currently priced at $27 a share. John just received a rights offering with a price of $23 plus 4 rights. John would like to purchase 4,000 shares of this new offering. To do this, John should: A. Exercise his entire option and wait for another offer to buy the balance of the shares he desires. B. Exercise his entire option and oversubscribe for 1,000 shares. C. Exercise his entire option and agree to a standby underwriting. D. Request an oversubscription of 4,000 shares at the offer price. E. Exercise his entire offer that will give him the total shares he desires