C-03-Q065mediumsingle_mcqআলোর বেগ কত?a3×1063 \times 10^{6}3×106 m/sb3×1073 \times 10^{7}3×107 m/sc3×1083 \times 10^{8}3×108 m/sd3×10103 \times 10^{10}3×1010 m/s