Suppose That we use A stack to transform an Infix with m operation and n operators to its corresponding postfix expression $($Note: operators include $+-*/).$ In the following, which one describes the size of the stack most appropriately?

$($A$)0(\frac{n}{m})$

$($B$)O(n)$

$($C$)O(mn)$

$($D$)0(m+n)$