During the Preparatory Reaction of Aerobic Respiration What Happens to the Carbon

During the preparatory reaction of aerobic respiration what happens to the carbon molecules?

A) the carbon molecules are broken down from a 3-carbon to a 2-carbon acetyl group and a 1-carbon CO₂ is released
B) the carbon molecules are broken down from a 4-carbon to a 3-carbon acetyl group and a 2-carbon CO₂ is released
C) the carbon molecules are converted from a 2-carbon to a 3-carbon acetyl group and a 1-carbon CO₂ is consumed
D) the carbon molecules are broken down from a 3-carbon to a 1-carbon acetyl group and two 1-carbon CO₂ are released