Dante's decision to invoke the muses is notable because

The correct answer is:

It reveals his respect for artistic tradition.

Epic novels were traditionally followed the Hero's Journey plot line and often invoked the muse. The Iliad and the Odyssey are the most notable examples of this before Dante's Inferno. And since Dante's Inferno too applies these epic characteristics (poetry form, the Hero's Journey, and invoking the muse), the story is joining in that tradition.

glamis thou art, and cawdor; and shalt be what thou art promis'd; yet do i fear thy nature; it is too full o' the milk of human kindness to catch the nearest way: thou wouldst be great; art not without ambition; but without the illness should attend it. what thou wouldst highly, that wouldst thou holily; wouldst not play false, and yet wouldst wrongly win: thou'dst have, great glamis, that which cries, "thus thou must do, if thou have it: and that which rather thou dost fear to do than wishest should be undone." hie thee hither, that i may pour my spirits in thine ear; and chastise with the valor of my tongue all that impedes thee from the golden round, which fate and metaphysical aid doth seem to have thee crown'd withal.  

he lacks ambition.  

he is hesitant.  

he lacks courage.  

he has moral scruples.

anne started to write her events in her journal everyday considering it someone would find it .