Let G be the grammar $($W$,\backslash$Sigma $,$R$,$S$),$ where W$=$S$,$A$,$N$,$V$,$P$\backslash$cup $\backslash$Sigma $,....(20$ points$)$ Let G be the grammar $($W$,\backslash$Sigma $,$ R$,$ S$),$ where $[$ W$=\{$S$,$ A$,$ N$,$ V$,$ P$\}\backslash$cup $\backslash$Sigma $,\backslash$cup E$=\{$ elephant, big, mouse, small, chased $\},$; R$=\{$P$->$N$,$; P$->$AP$,$; S$->$PVP$,$; A$->$ small,; A$->$ big,; N$->$ elephant,; N$->$ mouse $,$; V$->$ chased $\}.]$ Draw a parse tree for the following example string: "big mouse chased small elephant". Is this grammar ambiguous? Explain your reasoning.