I believe the answer is c)
<span>A. endoskeleton
</span>Endoskeleton is not a characteristic of Arthropods that has attributed to their diversity and success. Endoskeleton is defined as inner characteristics of the skeletal feature of an organisms such as bears, humans, fish and etc.
Exoskeleton on the other hand is the trait by which arthropods posses. It is skeletal feature that is described outside or is extrinsic, this is evident as crabs have their skeletons outside of their body.
Answer: Mitochondria
Explanation: Mitochondria is an organelle responsible for cellular respiration which is the break down of Simple sugars into carbon dioxide,water,ATP( adenosine trisphosphate).
It has a double membrane,known as the power House of the cells found in the cytoplasm of most Eukaryotic organisms.The number of Mitochondria found in an organism varies according to the Oxygen requirements of that organism. In human liver contains about 2000 Mitochondria,the Red blood cells do not contain Mitochondria.