Answer:
Atomic Theory
Explanation:
Atomic theory is the scientific theory that matter is composed of particles called atoms.Atoms are made of a nucleus,orbited by electrons, and combine to form various
substances.
Descendants are relatives of a person that down from one generation to the next. Parent to child to grandchild to great-grandchild.
A fetus is more developed than an embryo. So the last answer would be correct.
The answer is A. Differentiation