4. There are different forms of market efficiency in security market: weak form, semi-strong form and strong form. (a) Explain the concept of efficient market hypothesis and each of its three forms. (10 Marks) (b) Discuss two examples of the empirical evidence that support the semi-strong form of the market efficiency. (20 Marks) (c) Discuss two examples of the empirical evidence that refute the semi-strong form of the market efficiency (20 Marks) (Total 50 Marks)