Five persons entered the lift cabin on the groud floor of an 8 floors house. Suppose that each of them, independent and with equal probability can leave the cabin at any of floor beginning with the first. Find put the probability of all five persons leaving at different floors.

Options

A. `(""^(7)C_(5))/(7^(5))`
B. `(""^(7)C_(5)xx 5!)/(5^(7)`
C. `(""^(7)C_(5) xx5!)/(7^(5))`
D. `(5!)/(7^(5))`

Answer

C