If n pigeons are assigned to m pigeonholes then one of the pigeonholes must contain at least ______ pigeons.
1
\(\left( \dfrac{n-1}{m} \right) + 1\)
2
\(\left( \dfrac{n-1}{m} \right) \)
3
\(\left( \dfrac{n}{m} -1 \right) \)
4
\(\left( \dfrac{n+1}{m} \right) -1\)