R10.5 Suppose r contains a reference to a new Rectangle(5, 10, 20, 30). Which of the following assignments is legal? (Look inside the API documentation to check which interfaces the Rectangle class implements.) a. Rectangle a = r; b. Measurable e = r; c. Shape b = r;

d. Serializable f = r; e. String c = r; f. Object g = r; g. ActionListener d = r;