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A relation R defined by R = {(2, 1), (3, 1), (4, 2)} is a function because:
AAll ordered pairs are listed
BThe relation maps to natural numbers
CEvery first-coordinate (2, 3, 4) has a unique image
DThe same image (1) is shared by two domain elements
Answer & Solution
Correct answer: C. Every first-coordinate (2, 3, 4) has a unique image
A function requires every element of the domain to have ONE AND ONLY ONE image. R has domain {2, 3, 4} with images 1, 1, 2 respectively — each first-coordinate has a unique image. Sharing of images across different domain elements is fine (not a many-to-one violation).
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