Place the Following Steps of a Botnet Attack into Correct

Place the following steps of a botnet attack into correct order.
-Third

A) A spammer (or criminal) buys access to the botnet from the botmaster
B) The botmaster or spammer sends instructions to the infected PCs using the IRC server, which triggers them to send out spam messages to other servers
C) A botmaster sends out viruses to infect computers
D) Infected PCs follow instructions to log in to an IRC server