Molecular basis of organ differentiation depends on the modulation in transcription by

Organ differentiation is the result of differential gene expression: different sets of genes are switched on and off in different cells.
In eukaryotes gene expression is regulated mainly at the level of transcription.
Transcription factors are regulatory proteins that bind to specific DNA sequences (promoters and enhancers) and increase or decrease the rate at which particular genes are transcribed.
Different combinations of transcription factors are present in different cells, so they modulate transcription in a tissue-specific manner; for example the homeotic (Hox) genes that control the body plan code for transcription factors.
RNA polymerase is the enzyme that carries out transcription of all genes, but by itself it cannot select which genes are to be expressed; it depends on the transcription factors.
Ribosomes and anticodons (of tRNA) take part in translation, not in the modulation of transcription.
So the molecular basis of organ differentiation depends on the modulation of transcription by transcription factors.