Q81

Suppose we want to synchronize two concurrent processes $P$ and $Q$ using binary semaphores $S$ and $T$. The code for the processes $P$ and $Q$ is shown below.

$$\begin{array}{|l|l|}\hline \text{Process P:} & \text{Process Q: } \\\hline \text{ while(1) \{ } & \text{while(1) \{} \\ \text{W:} & \text{Y:} \\ \text{ print ‘0';} & \text{ print ‘1';} \\ \text{ print ‘0';} & \text{ print ‘1';} \\ \text{X:} & \text{Z:} \\ \text{\}} & \text{\}} \\\hline \end{array}$$

Synchronization statements can be inserted only at points $W, X, Y,$ and $Z$ Which of the following will ensure that the output string never contains a substring of the form $01^n0$ and $10^n1$ where $n$ is odd?