buddhata: @Tökömtele, yes, this is seki... @Farkas, if this is a beginner level tsumego, might as well explain to a beginner that seki is considered alive. This is something many beginners do not realize...
caranthir: Very well, but the solution is not seki; rather, the opponent can make (gote) seki after we have played the living move. But that possible continuation isn't shown here - the problem ends right after the living move as it should, since the seki is gote for the opponent and we need not (and should not) continue ourselves locally thereafter anyhow. The principle of Black stones being considered "alive" is that White can't remove those stones from board. This is such a basic (I'd say, the most basic) principle of the game) that anyone being capable of considering a possible seki in this case should also have a clear understanding of that principle. Moreover, several people are unhappy any time there's a superfluous hint like the one you are asking (especially here, where living is not gote seki for the player). Therefore I'd rather not add the hint here.
Very well, but the solution is not seki; rather, the opponent can make (gote) seki after we have played the living move. But that possible continuation isn't shown here - the problem ends right after the living move as it should, since the seki is gote for the opponent and we need not (and should not) continue ourselves locally thereafter anyhow. The principle of Black stones being considered "alive" is that White can't remove those stones from board. This is such a basic (I'd say, the most basic) principle of the game) that anyone being capable of considering a possible seki in this case should also have a clear understanding of that principle. Moreover, several people are unhappy any time there's a superfluous hint like the one you are asking (especially here, where living is not gote seki for the player). Therefore I'd rather not add the hint here.