b$)$ Junior equity analyst Penny attempted to draw the Securities Market Line $($SML$)$ to identify investment opportunities in the market. Along with risk$-$free Return $($rf$)$ and the market portfolio $($M$),$ Penny places four securities on the graph based on their risk and return characteristics. However, she left the chart incomplete, as shown below.

In the incomplete SML graph above, there are six securities A$,$ B$,$ C$,$ D$,E,$ and $F.$

$($Since I can't upload the image, I'll give a description, x axis is the beta and y asix is expected return. The x axis is spaced out in $0\mathrm{.}5$ units from $0$ to $2\mathrm{.}5,$ and the y axis is spaces out in $1$s from $0$ to $15\%.$ Point A $(0,4),$ B $(0\mathrm{.}5,10),$ C $(1,10)$ D $(1\mathrm{.}25,13)$ E $(1\mathrm{.}5,13)$ and F $(2,13).$ There are two horizontal line, first line runs from $10\%$ on y axis through point B and stopping at point C$,$ second long runs from $13\%$ on y axis through points D$,$ E and stops at point F$.$ Hope this helps paint a picture of the graph is you can't see it$)$

Identify which one of these is

i$)$ the risk$-$free security $($rf$)$

ii$)$ the market portfolio $($M$)$

Justify your answers with reasons.