All 50 Members of Johnson's family have at least one of the following characteristics: green eyes, dark hair, or pale

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All 50 Members of Johnson's family have at least one of the following characteristics: green eyes, dark hair, or pale skin. 20 members of Johnson's family have green eyes, 30 have dark hair,
and 40 have pale skin. If only 10 members of Johnson's family have all three characteristics, how many of them at least two characteristics?

A > 0

B > 10

C > 20

D > 30

E > 40

Answer: D

Source: Economist