In Wikipedia, look up "Colonization of Mars", read the intro and then scroll down to "Radiation", look at the plot of Compares of radiation doses, and answer this question: Compared to the US Annual Average of radiation exposure (Dose Equivalent), how much more radiation will an astronaut experience by traveling to Mars or living on its surface for 500 days (note that this plot is logarithmic)?
a) 2 times
b) 10 times
c) 20 times
d) 100 times
