The biosphere can best be defined as

These are the regions of the earth that are occupied by living organisms.

Hope this helps you!!^_^

The biosphere can be defined as the place where life occurs. It is a place rich in variety of plants, animals and many other life forms.

Explanation:

Biosphere can be defined as the place where there is a interaction between the living and non living system. The living forms of life like plants and animals  interact with soil, air and water in order to survive.

So, a biosphere can be defined as a place which is full of life.

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.

thinking it would be d not too sure but i think it's right