Step 1: Concept
The XOZ plane is the plane $y = 0$. The ratio in which a plane $y = 0$ divides the segment joining $(x_1, y_1, z_1)$ and $(x_2, y_2, z_2)$ is $-y_1 : y_2$.
Step 2: Meaning
Here $y_1 = -1$ and $y_2 = 3$.
Step 3: Analysis
Ratio $\lambda : 1 = -(-1) : 3 = 1 : 3$.
Step 4: Conclusion
Thus, $\lambda = 1/3$.
Final Answer: (C)