Correct option is B
Paedomorphosis refers to the retention of juvenile features in the adult form of an organism. In the case of the options provided:
- Oikopleura: This organism is a paedomorphic tunicate, as it retains juvenile features throughout its life, such as a larval body plan.
- Branchiostoma (also known as Amphioxus or lancelets): This organism does not exhibit paedomorphosis. It has a simple, adult body form that lacks retention of juvenile traits, so it is not paedomorphic.
- Ambystoma (specifically Ambystoma mexicanum, the axolotl): This organism is an example of paedomorphosis because it retains juvenile features, such as external gills, throughout its adult life.
- Triturus (a genus of salamanders, including species like the newt): This genus shows paedomorphosis as it may retain juvenile features in some species, such as the retention of gills in the adult.
Thus, Branchiostoma is the only organism listed that is not paedomorphic.
