Derive AV for this circuit assuming RL=50Ω, draw the transfer function on the second plot above, and label AV.

This is a small-signal problem built up towards a transfer function. Suppose the MOSFETs drawn have ID=1 mA when VGS=2.5 V, and Vth=0.5 V.
(a) Derive AV for this circuit assuming RL=∞, draw the transfer function on the first plot above, and label AV. Explain whether you expect clipping or not.
(b) Derive AV for this circuit assuming RL=50Ω, draw the transfer function on the second plot above, and label AV.
(c) Derive AV for this circuit assuming RL=50Ω and a coupling capacitor C, draw the transfer function on the third plot above, and label AV.