What mood does the alliteration in this excerpt help create?

a. astonished
b. curious
c. alarming
d. irksome

[Macbeth.] Ay, and since too, murders have been perform’d
Too terrible for the ear: the times have been,
That, when the brains were out, the man would die,
And there an end; but now they rise again,
With twenty mortal murders on their crowns,
And push us from our stools: this is more strange
Than such a murder is.