Signal travel time using speed of light

Steps:

• Convert height to meters: 300 km = 3 × 10^5 m.
• Minimum distance is the orbital height: d = 3 × 10^5 m.
• Apply formula t = d / v, where v = 3 × 10^8 m/s.
• Compute t = (3 × 10^5) / (3 × 10^8) = 10^{-3} s.

Why C is correct:

• Formula t = d/v with given values yields exactly 10^{-3} s due to cancellation of factors of 3 and 10^5/10^8.

Why the others are wrong:

• A: Uses 1.0 × 10^{-3} notation implying extra precision beyond the exact simplified result.
• B: Equals time for 600 km (double distance), likely from assuming round-trip instead of one-way.
• D: Same as B (2 × 10^{-3} s), twice the one-way travel time.

Final answer: C