Explaining the Differentiation of the Numerous Cell Types in a Mature

Explaining the differentiation of the numerous cell types in a mature organism from the initial zygote has been challenging. Which statement best summarizes the current understanding of the process?

A) Selective DNA replication; prior to cell division, only the DNA appropriate for the daughter cells' intended differentiation becomes available.
B) Selective chromosome movement; daughter cells receive only those chromosomes containing the appropriate genes required for their differentiation during cell division.
C) Selective gene expression; only specific genes are activated in particular cells.
D) Selective survival; only those cells randomly producing the appropriate protein survive, the remainder undergo apoptosis.