c$.$ Suppose all nodes are implementing the Slotted Aloha protocol. For each message, indicate the time at which each transmission begins.

d$.$ Which messages transmit successfully?

e$.$ Which protocol has better efficiency? $($Aloha$/$Slotted Aloha$)$

Consider the figure below, which shows the arrival of $7$ messages $($numbered message $1,2,3..\mathrm{.}7)$ for transmission at different multiple access wireless nodes at times $t=\{0\mathrm{.}9,1\mathrm{.}2,2\mathrm{.}4,3\mathrm{.}7,3\mathrm{.}9,4\mathrm{.}2,4\mathrm{.}8\}$ and each transmission requires exactly one time unit. $(2$ points per question$)$

a$.$ Suppose all nodes are implementing the Aloha protocol. For each message, indicate the time at which each transmission begins.

b$.$ Which messages transmit successfully? Write your answer as a comma separated list with no spaces using the messages' numbers.