I think the answer is the moon in its orbit around the Earth
The *heart* is the main organ of the circulatory system.
The circulatory system consists of three independent systems that work together: the heart (cardiovascular), lungs (pulmonary), and arteries, veins, coronary and portal vessels (systemic). The system is responsible for the flow of blood, nutrients, oxygen and other gases, and as well as hormones to and from cells.
Answer:
Option C
Explanation:
The null hypothesis is the problem statement and alternative hypothesis is counter of the null hypothesis.
Hence, the null hypothesis here is the rate of extinction was neither higher nor lower when there were sudden climatic changes (asteroid strike)
And alternate hypothesis is "the rate of extinction was either higher or lower when there were sudden climatic changes (asteroid strike)"
Hence, option C is correct
