Recapitulation theory forms
A. Anatomical evidence
B. Taxonomical evidence
C. Physiological evidence
D. Embryological evidence

Hint: Recapitulation theory was given by Haeckel. It states that organisms throughout their embryonic development have constant stages as throughout their evolution.

Complete answer: Recapitulation theory forms embryological evidence. For example, the human embryo with gill slits within the neck was believed by philosophers to solely signify an animal root, however, it described a complete animal stage in the development. Gill slits don't seem to be identical as gills and don't seem to be useful. Gill slits square measure the invaginations between the gill pouches or tubular cavity pouches, and that they open the tubular cavity to the surface. Gill pouches seem altogether crenated animal embryos. In mammals, the primary gill arch (in the primary gill pouch) develops into a jowl (Meckel's cartilage), the hammer and therefore, the auditory ossicle. AAT exceedingly late stage, all gill slits shut, with solely the ear gap remaining open. Ernst Haeckel studied animals and evolution in European nations from 1834 to 1919. He projected the multiplication law, whereas, functioning at the University of Battle of {jena|pitched battle} in Jena, Germany, in his 1866 book, Generelle Morphologie der Organismen [General Morphology of the Organisms]. The publication unifies theories Haeckel projected throughout his work throughout the decade and decade. Haeckel cited Johann Wolfgang von novelist from a European nation, Jean Baptiste natural scientist from France, and Charles Robert Darwin from England as his main influences for making the multiplication law.
Hence, the correct answer is option D.

Note: Haeckel projected the multiplication law once reading Charles Darwin's theories within the Origin of Species. Haeckel championed Darwin's theory of evolution in European nations and praised him for victimization data from biology to assist type his theory of evolution. Darwin argued that one might make a case for facts concerning biology, like the first similarity between embryos of various species, by viewing them in terms of evolution by the survival of the fittest.