9. Glycolytic skeletal muscle fibers...

A. demonstrate higher resistance to fatigue than oxidative fibers.

B. have a smaller diameter than oxidative fibers

C. have a higher density of mitochondria than oxidative fibers

D. have a lower concentration of myoglobin than oxidative fibers

The correct answer is D.

Explanation:      

Glycolytic skeletal muscle fibers are also called fast glycolytic muscle fibers. The produce Adenosine triphosphate (ATP) very quickly.

ATP refer to the molecule that carries energy inside our cells. It is also known as a high-energy molecule that warehouses energy and supplies the cell with it when it is required.

Because Glycolytic muscle fibers contain larges units of glycogen, they are able to respond very quickly by producing tension fast.

Unlike other skeletal muscle fibres such as the slow and fast oxidative fibres, Glycolytic muscle fibers contain myoglobin and seem to be white in colour. This is because they do not require the anaerobic mechanism to generate the required energy.  

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the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.