a$)$ Sketch the Security Market Line $($SML$)$ on a diagram, clearly labelling the axes and key points on the line. $(3)$

b$)$ Discuss what the SML signifies about the relationship between risk $($as represented by beta$)$ and expected return on a security. $(3)$

c$)$ Having regard to two specific points on the Capital Market Line $($CML$),$ determine its equation. Discuss the practical implications and applicability of this equation in the context of finance and investment decision$-$making. $(3)$

d$)$ The equation of the CML involves several terms, each representing a crucial concept in finance. Provide a brief interpretation of each term within the context of the Capital Market Line relationship.