Calculate the speed of sound at 25°C given the speed at 0°C is 1000 m/s, assuming speed is proportional to the square root of absolute temperature.

The absolute temperature $T_K$ is calculated by adding 273.15 to the Celsius temperature $T_C$.
Initial temperature: $T_0 = 0^\circ \text{C} = 0 + 273.15 = 273.15 \text{ K}$
Final temperature: $T = 25^\circ \text{C} = 25 + 273.15 = 298.15 \text{ K}$

The speed of sound $v$ is proportional to the square root of the absolute temperature $T$:

Therefore, we can write the ratio of speeds at two different temperatures as:

Where $v_0$ is the speed at $T_0$, and $v_T$ is the speed at $T$.

Given $v_0 = 1000 \text{ ms}^{-1}$ at $T_0 = 273.15 \text{ K}$. We need to find $v_T$ at $T = 298.15 \text{ K}$.

$1044.759 \text{ ms}^{-1}$ rounds to $1045 \text{ ms}^{-1}$.

Comparing this to the given options:
(A) $1043 \text{ ms}^{-1}$
(B) $1044 \text{ ms}^{-1}$
(C) $1045 \text{ ms}^{-1}$
(D) $1042 \text{ ms}^{-1}$

The calculated value matches option (C).

The final answer is $\boxed{\text{C) } 1045 \text{ ms}^{-1}}$.