Answer:
C. Appearing to be calm and relaxed.
Step-by-step explanation:
The word "placid" literally means anything that appears to be calm and peaceful on the surface, with barely any or no movement.
The given excerpt from "The Monkey's Paw" by W.W. Jacobs gave a description of the White family before they encounter the monkey's paw. The image of the night before the 'curse' encountered them "was cold and wet" with the father-son duo playing a game of chess. On the side, near the fire was the mother observing the game. The very act of the father in putting his king at risk produced a sharp comment from the mother, who was calmly knitting. The word "placidly" in the given passage suggests that she appears to be calm and relaxed.