How do Arthur's knights first respond to the green knights challenge

The Knights were both afraid and astonished. Some were simply courteous.

"Therefore to answer was many a knight afraid,and all stunned at his shout and sat stock-stillin a sudden silence through the rich hall;as all had slipped into sleep so ceased their noise and cry. I think it not all in fear, but some from courtesy; to let him all should revere speak to him firstly."

After making his challenge, the Green Knight was initially met with stunned silence.

"If he had stunned them at first, stiller were thenall the host in the hall, the high and the low."