Final answer:
Increased gluconeogenesis activity in the liver due to the up-regulation of a metabolic process that produces NADH leads to an B. increase in plasma glucose concentrations.
Step-by-step explanation:
The question concerns the metabolic process known as gluconeogenesis (GNG), which is the synthesis of glucose from non-carbohydrate precursors in the liver.
When the metabolic process in the liver is up-regulated and produces more NADH, this is most likely to increase the rate at which GNG occurs because NADH is an essential cofactor needed in the gluconeogenesis pathway.
Therefore, associated with the up-regulation of this process, plasma glucose concentrations would be expected to rise significantly as the liver converts substrates such as amino acids, lactate, and glycerol into glucose to be released into the bloodstream.
This means that the correct answer to the question is B. plasma glucose concentrations will increase significantly as a result of increased gluconeogenesis activity in the liver, especially under conditions of fasting or low carbohydrate intake, when the body needs to maintain minimum blood glucose concentrations for organs such as the brain.