So in step three, we basically reduce the NAD plus into NADH and the H ion. And the two electrons essentially come from this molecule here. So this is the Hydride ion that is transferred onto the NAD plus to form the NADH. In the process, we essentially oxidize the isocitrate. So if this is reduced, then this is oxidized, and we form the alpha key to gluterate. And also in the process, this entire component, this carbon dioxide region, is basically released.