C

To determine the dimensional formula of the velocity of sound, we start with the concept of velocity itself.

**Step 1: Understanding Velocity**
Velocity is defined as the distance traveled per unit time. The formula is given by:
$$ v = \frac{s}{t} $$
where:
- $v$ is velocity,
- $s$ is distance,
- $t$ is time.

**Step 2: Dimensional Formulas**
The dimensional formula for distance ($s$) is $[L]$ (length), and the dimensional formula for time ($t$) is $[T]$.

**Step 3: Combining Dimensional Formulas**
Therefore, the dimensional formula for velocity ($v$) can be expressed as:
$$ [v] = [L][T]^{-1} $$

• Where $[L]$ represents the dimension of length.
• $[T]^{-1}$ indicates the inverse relation to time.

Hence, the dimensional formula of velocity is:
$$ [M^0 L^1 T^{-1}] $$
This corresponds to option C. Therefore, the correct answer is C.