Answer: True.
- A True
- B False, claiming the identity does not actually hold
- C Valid just for the special case r=2
- D Valid just for the special case n=r
Correct answer: A. True
Explanation: nPr = n!/(n-r)! and nCr = n!/[r!(n-r)!]. So nPr = r! × nCr. True.
Counting tree for selecting 2 items from {A, B, C} without repetition: 3 x 2 = 6 ordered arrangements.
Concept context
Counting, arrangements, and selections