Ten-point eye - possible seki
Difficulty: Intermediate Keywords: Life & Death
Therefore here must come first. After , prevents a 10000 year ko, which is usually preferable to seki for Black. Instead of , White can make a ko with . (Usually bad for White, however.)
Bill: White is in little danger, because the ko preserves the option of seki while taking sente.
White is one point worse off locally than with the seki in the first diagram. This could be best if Black has had to make a losing ko threat.