B

Reasoning: Radiographic and histologic studies show that the first permanent molar is the earliest‐forming tooth of the successional dentition; initial cusp calcification is already detectable in neonates, i.e., right at birth, and all later stages follow from this neonatal start point [Swindler, 1961, PMID 13774313; Anderson, 1976, PMID 1249551].