Using four colors, color all regions in the above diagram. Adjacent (sharing a common border) cannot have the same color. Record your answer in the comments section below.
Update and solution.
At first glance these appeared to be difficult. They are from a page of about six, of varying difficulty. Anyhow, given four colors to work with the logical approach was to work from the inside circle, using two colors, and then use the remaining two colors for the next ring out and so on. Here is my solution.