(;GM[1]FF[4]CA[UTF-8]AP[CGoban:2]ST[2]
RU[Japanese]SZ[19]KM[0.00]TM[]
PW[White]PB[Black]AW[rl][pm][rm][rn][oo][po][qo][op][oq][pq][qr][ps]AB[sn][ro][pp][qp][rp][qq][sq][rr]C[how can white best attack the black group?]PL[W]
(;W[rs]CR[rs]
;B[so]CR[so]
(;W[sr]CR[sr]C[RIGHT
white makes a ko])
(;W[ss]CR[ss]
;B[sr]CR[sr])
(;W[sm]CR[sm]
;B[sr]CR[sr]))
(;W[sr]CR[sr]
;B[rs]CR[rs]
(;W[so]CR[so]
;B[sp]CR[sp])
(;W[qs]CR[qs]
;B[ss]CR[ss])
(;W[sm]CR[sm]
;B[so]CR[so]))
(;W[ss]CR[ss]
;B[rs]CR[rs])
(;W[sm]CR[sm]
;B[rs]CR[rs])
(;W[sp]CR[sp]
;B[rs]CR[rs])
(;W[qs]CR[qs]
;B[rs]CR[rs])
(;W[so]CR[so]
;B[rs]CR[rs]))