We wish to use an NMOS transistor as a variable resistor with Ron = 500capital omega at VGS = 1 V and Ron = 400 capital omega at VGS = 1.5 V. Is it possible to design such NMOS transistor and why?

a). Yes, it is possible as long as we select the appropriate W/L.
b). Yes, it is possible when we choose appropriate Cox and W/L parameters.
c). No, it is not possible since the Ron is the same regardless of VGS.
d). No, it is not possible since no selection of Cox and W/L parameters can satisfy this requirement.
e). None of the above.