Suppose the Speed of Light Is Determined Experimentally to Be

Suppose the speed of light is determined experimentally to be 299,796 ± 4 km/s. If the total path length for your interferometer is exactly 11.0 m, how big an error in the time required for the light to travel through the apparatus corresponds to the uncertainty ±4 km/s) in the speed of light?

A) 4.9 × 10^-13 s
B) 2.7 × 10^-3 s
C) 3.7 × 10^-8 s
D) 4.9 × 10^-10 s
E) 9.2 × 10^-12 s