underrightarrow show a small arrow #9
Description
the underrightarrow key show a small arrow but i need to show a arrow.
the input is : $+[O]$ $\begin {matrix}\\\underrightarrow{KMnO_4}\\{KOH}\end {matrix}$ $A$ $\underrightarrow{NaOH}$ $B$ $\begin {matrix}\\\underrightarrow{NaOH}\\{CaO}\end {matrix}$ $C$.
the output is :
but i need this type of output
