Primordial germ cells are derivative of (LQ)
Pg. 13, Langman Embryology (Ed 11th), Pg. 186, Gray’s Anatomy (Ed 40th)
Primordial germ (PGCs) cells have been isolated from the epiblast at the posterior end of primitive streak in 2nd week.
Germ layers form in the 3rd week by the process of gastrulation.
Hence, PGCs cannot be considered as a derivative of any embryonic germ layers.
Though some investigators consider epiblast as primitive ectoderm, hence, ectoderm can be a choice as answer, if epiblast was not among the options.