Ratio of light to sound speed via known values

Steps:

• Speed of light in vacuum is $3 \times 10^8$ m/s.
• Speed of sound in air is approximately $3.4 \times 10^2$ m/s.
• Divide: $\frac{3 \times 10^8}{3.4 \times 10^2} \approx 0.88 \times 10^6 \approx 10^6$.
• Thus, the ratio approximates to $10^6$.

Why C is correct:

• The calculation directly yields $\approx 10^6$, matching the order of magnitude for the ratio using standard physical constants.

Why the others are wrong:

• A ($10^4$): Underestimates by factor of 100, ignoring the full magnitude of light's speed.
• B ($10^5$): Underestimates by factor of 10, too low for the precise division.
• D ($10^7$): Overestimates by factor of 10, exceeding the actual ratio.

Final answer: C