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Number of one-one and onto (bijective) functions from {1,2,3} to {1,2,3}:
A9
B27
C3
D3! = 6 (permutations)
Answer & Solution
Correct answer: D. 3! = 6 (permutations)
Bijections of n-element set to itself = permutations = n!. For n = 3: 3! = 6. (Cycle structures: identity, 3 transpositions, 2 three-cycles.)
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