What is the most likely reason that horses and mountain goats have hooves?
a. they have homologous structures because they have a common ancestor.
b. they have analogous structures because they have a common ancestor.
c. these are vestigial structures in both animals because they are not used.
d. these are similar structures due genetic mutations.

The correct answer is statement a.

Explanation:

The prevalence of shared ancestry between the genes or a pair of structures in different taxa is termed as homology. A common illustration of homologous structures is the forelimbs of vertebrates. A homologous structure refers to a bone or an organ that possess similar underlying anatomical characteristics, which is witnessed in various animals. These compositions hold the notion that distinct animals originated from a common ancestor and serve as the proof of evolution.

from my research i have to the conclusion that decomposers, such as fungi, bacteria and invertebrates, play a critical role in nutrient cycling and without them the earth's ecosystem may not support life as we know it. elements such as carbon, nitrogen and phosphorus exist in limited amounts on earth, although huge amounts of carbon are being released into the atmosphere from underground sources now by humans. it is still extremely important that other nutrients be retained by the process of re-use. decomposers are organisms that are able to chemically break down dead material and make these elements available for use by other organisms. without this breakdown of dead material, dead bodies would pile up. so decomposers also play a role in clean up also. without them, life might not continue as we know it and dead material would overwhelm the earth.    

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