Thanks for the question! So parts of this one isn’t actually super diagrammable. The first sentence you wouldn’t really diagram. The second sentence you certainly could diagram as
Human action —> Potentially has an explanation
And the third sentence you could then diagram
Action justified —> Person performing action has sufficient reasons for the action
The fourth sentence isn’t really easily diagrammable either. The last sentence could be diagrammed
Action rational —> Action whose justification (reasons for the action) form an essential part of its explanation
And seeing these, there’s not really a way to connect any of these statements with each other. So let’s see what’s the answer for this must be true question. Take a look at (E), which tells us that if any human actions are rational, then reasons must sometimes be causes of actions. In other words
Any human actions rational —> Reasons must sometimes be causes of actions
Now note that we’re told that if an action’s rational, then the reasons for the action form an essential part of its explanation. So that means if there are any human actions that are rational, then reasons do have to sometimes be the causes of actions.
Hope this helps! Feel free to ask any other questions that you might have.