(;GM[1]FF[4]AP[Sabaki:0.18.0]CA[UTF-8]KM[6.5]SZ[19]AB[pd][qe][rf][nc]AW[rg][pf][qf][qj]C[Position 4]PL[W]AE[rd][re]
(;W[re]C[W option 1]
;B[rd]
;W[sf]
)(;W[lc]C[W option 2]
(;B[ne]C[What's the W follow up?]
)(;B[re]
;W[qh]
;B[pp]C[What's the W follow up?

Can O18 form a living group if B blocks on the outside?]
)))