The three-carbon molecules broken down from six-carbon molecules of glucose during the first step in the process of nutrition inall organisms is called A. butane B. ethane C. pyruvate D. methane

The correct answer is C. pyruvate.

Pyruvate is a three-carbon molecule that is formed when glucose is broken down in the first step of cellular respiration. It is then used in the Krebs cycle, which is a series of chemical reactions that produce energy.

Butane is a four-carbon molecule, ethane is a two-carbon molecule, and methane is a one-carbon molecule. These molecules are not involved in the process of cellular respiration.

Here is a diagram of the glycolysis pathway, which is the first step in cellular respiration:

As you can see, glucose is broken down into two pyruvate molecules. These pyruvate molecules are then used in the Krebs cycle, which is the next step in cellular respiration.