Swishtacular Ltd was registered without a constitution. Cecil, Phil and Deidre are the directors. Deidre was previously appointed as the managing director. Which of the following is correct?

a. Deidre will cease to be managing director if she ceases to be a director.

b. The directors may revoke or vary Deidre's appointment as managing director.

c. The directors cannot revoke Deidre's appointment until they find a replacement managing director.

d. All of the above are correct.

e. A & B are correct, but C is incorrect.