Which systems work together so oxygen can be distributed to the cells of your body? How do these two systems work together to accomplish this task?

The human respiratory and circulatory systems work together to supply the body with oxygen and get rid of waste carbon dioxide.

 Our respiratory and circulatory systems have to work together, the respiratory system takes oxygen from the air we breathe into our lungs, the oxygen is transferred to the blood, the circulatory system then transfers the blood, which transfers the oxygen to the cells for the rest of the body.

Explanation: Edg 2020

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.

i believe it's c. the trait for large beaks will be passed on to future generations through natural selection.

since eventually smaller beaks would have to find another source of food or even eventually just die out from the lack of food.