The best answer would be Letter B - to entertain.
The author merely would like to provide amusement to the readers at his expense. It certainly does not persuade, explain, nor inform anything since it states - <span>But why bother with the descriptions; you’ve probably already grasped the idea!</span> - which could be taken as a witticism.
"<span>because they can deliver right to your door"
that's a subordinate clause </span>
