You are correct! Option A is the best summary of glycolysis.
In glycolysis, one 6-carbon glucose molecule is broken down into two 3-carbon pyruvate molecules, and this process occurs anaerobically (without oxygen). Glycolysis results in a net gain of 2 ATP molecules after accounting for the ATP used and produced during the process.
Option B incorrectly states that glucose forms ADP instead of pyruvate, and it also incorrectly suggests a net total of 4 ATP, which is not accurate for glycolysis.