The partial twinning that led to the births of conjoined twins Abby and Brittany Hensel must have happened during the first two weeks of gestation,because the girls
A)share tissues that descend from ectoderm,endoderm,and mesoderm.
B)share only tissues derived from mesoderm.
C)were born on time.
D)have two separate nervous systems.

Question

Quizplus · Accepted Answer

Sharing tissues from all three germ layers (ectoderm, endoderm, and mesoderm) indicates that the partial twinning event occurred very early in gestation, likely during the first two weeks when these germ layers are formed. This is consistent with what is known about conjoined twins and the development of the human embryo. B would not be correct as they share more than just mesodermal tissues. C is unrelated to the formation of conjoined twins. D is also irrelevant as having separate nervous systems does not necessarily indicate when the twinning occurred.

The Partial Twinning That Led to the Births of Conjoined