A millisecond and a microsecond are

${10}^{-3}s$ and ${10}^{-12}s,$ respectively.

${10}^{-2}s$ and ${10}^{-6}s,$ respectively.

${10}^{-6}s$ and ${10}^{-9}s,$ respectively.

${10}^{-3}s$ and ${10}^{-9}s,$ respectively.

${10}^{-3}s$ and ${10}^{-6}s,$ respectively.