For this case we have that by definition:
[tex]C (n, r) = \frac {n!} {r! * (n-r)!}[/tex]
So:
[tex]C (5,5) = \frac {5!} {5! * (5-5)!}\\C (5,5) = \frac {1} {0!}[/tex]
By definition:
[tex]0! = 1[/tex]
[tex]C (5,5) = \frac {1} {1} = 1[/tex]
Answer:
[tex]C (5,5) = 1[/tex]
Option B
