Nftion[x_]:=CDF[NormalDistribution[],x]

Nftion[0]

S0=100; r=0.04; σ=0.25; T=1; K=100

done[s_,t_]=(Log[s/K]+(r+σ^2/2)*(T-t))/σ/Sqrt[T-t]

dtwo[s_,t_]=done[s,t]-σ*Sqrt[T-t]

Call[s_,t_]= s*Nftion[done[s,t]]-K*E^(-r(T-t))*Nftion[dtwo[s,t]]

Call[100,0]

Clear[done,dtwo]

Plot3D[Call[x,y],{x,0,200},{y,0,1}]