In the chemical reaction shown below, the organic molecule $($yellow$)$ donates two electrons to NAD$+,$ which becomes NADH. Which of the following best describes the conversion of NAD$+$ to NADH?

Redox reaction where an organic molecule looses two electrons, and NAD gains two electrons to become NADH

Reduction Reaction

Synthesis Reaction

Oxidation Reaction

Decomposition Reaction