What is the connotative effect of the word pale, which is repeated so frequently throughout this poem?

Excerpt from La Belle Dame sans Merci

John Keats

'O WHAT can ail thee, knight-at-arms,

Alone and palely loitering?

The sedge is wither'd from the lake,

And no birds sing.4

'O what can ail thee, knight-at-arms,5

So haggard and so woe-begone?

The squirrel's granary is full,

And the harvest 's done...

'I saw pale kings and princes too,

Pale warriors, death-pale were they all;

They cried—"La belle Dame sans Merci

Hath thee in thrall!"40

 What is the connotative effect of the word pale, which is repeated so frequently throughout this poem?

A)It describes the color of the knight's skin accurately--he has a fair complexion.  

B)It suggests a purity and innocence on behalf of the Knight and his beautiful lady.  

C)It emphasizes the old age of the Knight and other characters mentioned in the poem.  

D)It conveys the sickly, fear-drenched, and weakened atmosphere surrounding the knight.

The answer is D)  It conveys the sickly, fear-drenched, and weakened atmosphere surrounding the knight.

? ? what can you explain this to me i am so confused