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Combinatorics Difficulty 2.0 Junior Find the answer United Kingdom

Alan, Bella, Claire, Dora, and Erik met together and shook hands exactly once with everyone they already knew. Alan shook hands once, Bella shook hands twice, Claire shook hands three times and Dora shook hands four times. How many times did Erik shake hands?

(A) $1$ (B) $2$ (C) $3$ (D) $4$ (E) $5$

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