Which of the following statements about the interaction of earth’s systems is true?
a.
the interaction between earth’s systems is limited to a response to human activity.
b.
the earth’s system interact using positive feedback only.
c.
the earth’s systems interact using negative feedback only.
d.
all of the earth’s systems interact with each other.

The correct answer is option d. "All of the Earth’s systems interact with each other".

Explanation:

Earth’s systems are interconnected parts that by functioning in harmony allow that the planet maintain a relative equilibrium. The five major systems of the Earth are Geosphere, Biosphere, Cryosphere, Hydrosphere and Atmosphere. All of the Earth’s systems interact with each other and anything that would affect any of the systems, affects all of them.

the answer is d.) homologous; have mammary glands

the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.