$$P - 2,\,Q - 1,\,R - 3,\,S - 4$$

$$P - 1,\,Q - 3,\,R - 2,\,S - 4$$

$$P - 1,\,Q - 2,\,R - 3,\,S - 4$$

$$P - 3,\,Q - 2,\,R - 1,\,S - 4$$

$${\rm I}$$ & $${\rm I}V$$ only

$${\rm I}$$ & $${\rm III}$$ only

$${\rm I}$$ only

$${\rm I}V$$ only

$$\left\{ {w{w^R}} \right.\left| {w \in \left\{ {0,\,1} \right\}\left. {^ + } \right\}} \right.$$

$$\left\{ {w{w^R}} \right.x\left| {x,w \in \left\{ {0,\,1} \right\}\left. {^ + } \right\}} \right.$$

$$\left\{ {wx{w^R}} \right.\left| {x,w \in \left\{ {0,\,1} \right\}\left. {^ + } \right\}} \right.$$

$$\left\{ {xw{w^R}} \right.\left| {x,w \in \left\{ {0,\,1} \right\}\left. {^ + } \right\}} \right.$$

$$1$$

$$2$$

$$3$$

$$4$$