What is the effect of the alliteration in the closing lines of "Ozymandias": "boundless and bare, / the lone and level sands stretch far away"?

AIt produces feelings of pity for the death of the king.
BIt stresses the challenges of life in the desert.
CIt brings the poem back to the sculptor's perspective.
DIt focuses attention on the vast, empty space in which the statue is decaying.