1. We need the dimensional formula of a quantity whose SI unit is pascal-second.

2. First, write pascal in terms of fundamental units: $1\,\text{pascal} = 1\,\text{Pa} = 1\,\frac{\text{N}}{\text{m}^2}$

3. Now, the unit of force is: $1\,\text{N} = 1\,\text{kg}\cdot \text{m}\cdot \text{s}^{-2}$ So, $1\,\text{Pa} = \frac{\text{kg}\cdot \text{m}\cdot \text{s}^{-2}}{\text{m}^2} = \text{kg}\cdot \text{m}^{-1}\cdot \text{s}^{-2}$

4. Therefore, the dimensional formula of pascal is: $[\text{Pa}] = [M L^{-1} T^{-2}]$

5. The given unit is pascal-second: $\text{Pa}\cdot \text{s}$ Multiply the dimensions of pascal by $T$: $[M L^{-1} T^{-2}] \cdot [T] = [M L^{-1} T^{-1}]$

6. So the required dimensional formula is: $[M L^{-1} T^{-1}]$

7. Compare with options:

   • A: $[M L^{-1} T^{-1}]$ ✅
   • B: $[M L^{-1} T^{-2}]$
   • C: $[M L^2 T^{-1}]$
   • D: $[M^{-1} L^3 T^0]$

Hence, the correct option is A.