A student wrote following code for their homework in "Bioprocess Modelling" course. In the homework, the student was supposed to model and simulate microbial growth in a stirred tank bioreactor.Based on the code given below, answer the following questions.$\%\%\%\%\%$mumax$=0\mathrm{.}20$;Ks$=1\mathrm{.}00$;Yxs$=0\mathrm{.}5$;Ypx$=0\mathrm{.}2$;mu $=$ @$($S$)$ mumax$*$S$./($Ks s$)$;Rg $=$ @$($X$,$S$)$ mu$($S$)*$X;Rs $=$ @$($X$,$S$)-1/$Yxs$*$Rg$($X$,$S$)$;Rp $=$ @$($X$,$S$)$ Ypx$*$Rg$($X$,$S$)$;init$=[0\mathrm{.}10$; $20\mathrm{.}0$; $0\mathrm{.}0]$;dX $=$ @$($t$,$y$)$ Rg$($y$(1),$y$(2))$;dS $=$ @$($t$.$y$)$ Rs$($y$(1),$y $(2))$;dP $=$ @$($t$,$y$)$ Rp$($y$(1),$y$(2))$;statefun $=$ @$($ty$)[$d$($t$,$y$)$; dS$($t$,$y$)$; dP$($t$,$y$)]$;$\%$ Use ode$45$ for the integration.tspan $=[030][$t$,$y$]=$ ode$45($statefunc$,$tspan,init$)$;$\%\%\%\%\%1.$ Which mode of operation is assumed by the student? Justify your answer$\mathrm{.}2.$ What are the state variables in the model?$3.$ What are the parameters in the model?$4.$ Give one assumption that was assumed by the student who derived the model equations.