I think the correct answer would be A. The yolk sac becomes the placenta. It is membranous sac that is attached to the embryo. It provides all the nutrition and the blood cells needed by the embryo. It is also called the umbilical vesicle.
Answer:
Centre of Gravity
The centre of gravity (COG) of the human body is a hypothetical point around which the force of gravity appears to act. It is point at which the combined mass of the body appears to be concentrated[1]. Because it is a hypothetical point, the COG need not lie within the physical bounds of an object or person. One subjective way (there are objective measures) to approximate the COG of an object is to visualise it balancing on one finger.
Centre of Gravity in the Human Body
In the anatomical position, the COG lies approximately anterior to the second sacral vertebra. However, since human beings do not remain fixed in the anatomical position, the precise location of the COG changes constantly with every new position of the body and limbs. The bodily proportions of the individual will also affect the location of the COG.
Answer:
When wolves were removed from the habitat, the elk thrived, causing a population increase. more elk means an increase in the need for food. The leaves of an aspen tree make good food for elk causing over-grazing and soon, the "aspen trees will be eaten out."
Explanation:
Krypton helps geologist determine the absolute age of a rock
