$\begin{array}{1 1} \text{(a) Mouth->Stomach Small intestine -> Oesophagus ->Large intestine} \\ \text{
(b) Mouth -> Oesophagus -> Stomach -> Large intestine -> Small intestine} \\ \text{
(c) Mouth -> Stomach -> Oesophagus -> Small intestine -> Large intestine} \\ \text{
(d) Mouth -> Oesophagus -> Stomach -> Small intestine --> Large intestine}
\end{array}$