Net ATP formed in glycolysis is

**Core Concept**
Glycolysis is the first step in cellular respiration, a metabolic pathway that converts glucose into pyruvate, generating a small amount of ATP and NADH in the process. This process occurs in the cytosol of cells and is essential for energy production in the absence of oxygen.

**Why the Correct Answer is Right**
In glycolysis, two molecules of ATP are consumed, but four molecules of ATP are generated, resulting in a net gain of two ATP molecules. This is achieved through the conversion of glucose to pyruvate, which involves the formation of several high-energy intermediates, including 1,3-bisphosphoglycerate and phosphoenolpyruvate. These intermediates are then converted into pyruvate, generating ATP in the process.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because glycolysis does not result in the net loss of ATP.
**Option B:** This option is incorrect because glycolysis generates ATP, not NADH.
**Option C:** This option is incorrect because the correct net gain of ATP in glycolysis is two molecules, not four.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that glycolysis is a crucial step in cellular respiration, and understanding the net gain of ATP is vital for appreciating the overall efficiency of energy production in cells.

**Correct Answer: C. 2**