Answer :
[tex]1m=100cm\to1cm=0.01m\\1h=60min\to1min=\frac{1}{60}h\\========================\\\\4.6\times10^8\ cm/min=4.6\times10^8\times\frac{0.01m}{\frac{1}{60}h}=4.6\times10^8\times0.6\ m/h\\\\=\boxed{2.76\times10^8\ m/h}\\\\Answer:\fbox{A.}[/tex]