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Let A be the set of 4-digit numbers a1 a...

Let A be the set of 4-digit numbers `a_1 a_2 a_3 a_4` where `a_1 > a_2 > a_3 > a_4`, then `n(A)` is equal to

A

126

B

`.^(10)C_(4)`

C

210

D

None of these

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The correct Answer is:
b,c
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