Couldn't believe I couldn't find this position in the pattern search. Seems like such a basic position. Anyway, please comment if there are any mistakes/omissions. Note: this is a best move problem, I'm normally not picky but this time I was.
(;AB[ir]AB[hq]AB[ip]AB[lq]AB[jq]AW[jp]AW[kq]AW[jr]LB[jr:1]C[How to respond to White 1?]AW[kn]AB[oq]AB[np]AW[ln]AP[goproblems]
(;B[kp]
(;W[iq]C[White thinks it is a ko. Play K if you want a ko threat.]LB[nq:K]
(;B[jo]
(;W[jq]
(;B[js]C[RIGHT])
(;B[kr]C[RIGHT])))
(;B[nq]C[Wasted a ko threat])
(;B[kr];W[jo];B[jq]C[Missed an opportunity to get the K4 stone]))
(;W[kr];B[jo];W[lr];B[mq]C[Can't be a good result for w])
(;W[jo]C[This minimizes losses]))
(;B[iq]C[This is exactly what White wants. White can now choose A or B and if Black cuts White gets to atari and subsequently capture the M3 stone.]LB[kr:A]LB[kp:B])
(;B[kr];W[kp]C[Acceptable result, but you could have captured the L3 stone.])
(;B[jo];W[kp])
(;B[lr]C[Might as well play L2])
(;B[lp];W[kp]))