Answer the following question: I'm taking a test and have to guess the right answer to the question after the article. Article: Hercule Poirot looked over the small gate which gave admission to Pine Crest. It was a modern nicely-built house. It was on a hill top, and the hill top was planted with a few sparse pines. It had a small neat garden and a large elderly man was watering with a big tin. Spence's hair was now grey all over. He had not shrunk much in girth , though. He stopped watering and looked at the visitor at the gate. Hercule Poirot stood there without moving. "God bless my soul," said Spence. "It must be. It can't be but it is. Yes, it must be Hercule Poirot!" "Aha," said Poirot, "you remember me. I'm grateful." Spence abandoned the watering can and came down to the gate. "What brings you down here?" "What has brought me to many places in my time," said Poirot, "and what once a good many years ago brought you to see me. Murder, Spence." "I'm done with murder since I retired," said Spence, "except in the case of weeds. Killing weeds is never easy as you think, something's always wrong. How did you know where to find me?" he asked as he opened the gate and Poirot passed through. "You sent me a Christmas card. It had your new address on it." "Ah yes, so I did. I'm old-fashioned, you know, I like to send round cards at Christmas time to a few old friends. I'm an old man now." "We both are." "Not much grey in your hair," said Spence. "I take care of my hair with a bottle," said Poirot. "There is no need to appear in public with grey hair unless you wish to do so. By the way, why have you come to live in Woodleigh Common?" "As a matter of fact, I came here to join forces with a sister of mine. She lost her husband, her children are married and living abroad. So I moved in here. Pensions don't go far nowadays, but we do comfortably living together." Question: From their dialogue, we can learn about _ . Options: A: their common friends B: Spence's sister's characters C: their relationship D: Poirot's recent life
Answer:
C