Step 1: Concept
The relative refractive index of medium 2 with respect to medium 1 is defined as the ratio of the absolute refractive index of medium 2 to the absolute refractive index of medium 1: ${}^{1}\mu_{2} = \frac{\mu_2}{\mu_1}$.
Step 2: Meaning
Here, we are looking for the refractive index of glass ($g$) with respect to water ($w$), which mathematically corresponds to ${}^{w}\mu_{g} = \frac{\mu_g}{\mu_w}$.
Step 3: Analysis
We are given the absolute refractive values: $\mu_w = \frac{4}{3}$ and $\mu_g = \frac{3}{2}$. Substituting these values into the fraction yields: ${}^{w}\mu_{g} = \frac{3/2}{4/3} = \frac{3}{2} \times \frac{3}{4} = \frac{9}{8}$.
Step 4: Conclusion
Therefore, the relative refractive index of glass with respect to water is equal to $9/8$.
Final Answer: (A)