First reduction in pentose phosphate pathway is
A) Oxidation of 6-phosphogluconate
B) Oxidation of fructose 6-phosphate
C) Oxidation of glucose 6-phosphate
D) Oxidation of fructose 5-phosphate

Hint: The first carbon molecule needed for the pentose phosphate pathway allows the breakdown of the basic sugar, glucose, in glycolysis.

Complete answer:
First we should know about the pentose phosphate pathway to answer this question. Every living organism has a series of blueprints called DNA and RNA in each of its cells and they are important to life as they are the evidence on how to create the structures of protein that constitute each and all of us. There are many layers of quality control to help avoid and correct errors when DNA and RNA are initially made, given the structural and functional significance of DNA and RNA for all living things. Although glycolysis products are sent to generate energy from the remainder of cellular respiration, there is also an alternate branch of glycolysis to generate the sugars that make up DNA and RNA. This pathway, called the Pentose Phosphate Pathway. It is a unique pathway because in this pathway no energy is generated or used in the form of adenosine triphosphate (ATP). The oxidative phase and the non-oxidative phase are the first of two steps of the pentose phosphate pathway.
Now, let us find the solution from the options-
>The breakdown of a molecule as it loses at least one of its electrons is oxidation. To form lactone, Glucose-6-phosphate is oxidised. NADPH is formed as a by-product of this reaction which is reduced as glucose-6-phosphate is oxidized. Another reaction, catalysed by a different enzyme, needs water to form 6-phosphogluconate, the linear product, following the glucose-6-phosphate oxidation.
Thus, the options A, B, and D are incorrect.

Thus, the correct answer is option ‘C’ Oxidation of glucose 6-phosphate

Note:A metabolic pathway parallel to glycolysis is the pentose phosphate pathway. It produces NADPH and pentoses and also 5-phosphate ribose, a precursor for nucleotide synthesis. Although oxidation of glucose is involved in the pentose phosphate pathway, its primary role is anabolic instead of catabolic. In red blood cells (erythrocytes), the mechanism is highly important.