The product of the third step of glycolysis is

Explanation

In the glycolytic pathway, the third step involves the phosphorylation of fructose 6-phosphate to form fructose 1,6-bisphosphate. This reaction is catalyzed by the enzyme phosphofructokinase-1 (PFK-1) and is a key regulatory step, often considered the rate-limiting step of glycolysis. The correct answer is fructose 1,6-bisphosphate. The other options are incorrect, as they represent different stages or molecules involved in the glycolytic process: Glucose is the initial substrate, glucose 6-phosphate is the product of the first phosphorylation step, and fructose 6-phosphate is the product of the second step.