Answer the following question given this paragraph: 

The pyruvate molecules from glycolysis next enter the matrix of a mitochondrion. That's where the second stage of cellular respiration takes place. This stage is called the Krebs cycle . During this stage, two more molecules of ATP are produced. Other energy-storing molecules are also produced (to be used to make more ATP in stage 3). The Krebs cycle requires oxygen. Anything that needs oxygen is described as aerobic . The oxygen combines with the carbon from the pyruvate molecules. This forms carbon dioxide, a waste product.


Q: What is the second stage of cellular respiration?

 Choices:

- beatnik cycle

- duocycle

- marr cycle

- krebs cycle

A:
krebs cycle
