When does the embryo form?
A. At the end of the first trimester
B. In the second trimester.
C. A few days after fertilization
D. At the end of the third trimester.

C. A few days after fertilization.

Explanation:

During the first two weeks, the embryo moves through the uterine tube to the uterus where it will implant. The differentiation that establishes the organ systems takes place between 3 and 8 weeks in the first 8 weeks following fertilization.

only about ten percent of the energy at one trophic level is passed on to organisms at the next trophic level. the remainder of the energy is used in life processes or lost as heat.