Which of the following is a CONTRAINDICATION to placing a stainless steel crown (SSC) on a primary molar?

Stainless steel crowns (SSC) are indicated for: following pulp therapy, multi-surface caries, developmental defects (hypoplasia, amelogenesis/dentinogenesis imperfecta), and as abutments for space maintainers. An infraoccluded (ankylosed) primary molar is a CONTRAINDICATION. An ankylosed tooth lacks a functional periodontal ligament and will not exfoliate normally; placing a crown on it serves no benefit since the tooth cannot erupt further and may block the permanent successor. Additional SSC contraindications: more than half the root is resorbed (near natural exfoliation), non-restorable crown due to severe destruction, and known nickel allergy. Infraocclusion is the classic 'except' answer because all other options listed are established indications for SSC.