Which of the following is correct concerning the Williams Act and the corresponding SEC rules thereunder?

a. Only shareholders tendering after a bidder has increased the offering price will be paid the higher price.

b. Shareholders who tender during a subsequent offering period will have no withdrawal rights.

c. The bidder must accept shares from tendering shareholders at a first-come, first-served basis.

d. The management of the subject company must inform its shareholders of its position on the tender offer within 20 days after the offer has been made.