To solve this problem, we need to identify which of the given options is not a product of the light reaction of photosynthesis. Let's analyze each option:$\newline \bullet$NADPH:$\newline$ - During the light reactions of photosynthesis, NADP$^+$ is reduced to NADPH.$\newline$ - Therefore, NADPH is a product of the light reaction.$\newline \bullet$NADH:$\newline$ - NADH is not produced during the light reactions of photosynthesis.$\newline$ - It is typically involved in cellular respiration, not photosynthesis.$\newline$ - Therefore, NADH is not a product of the light reaction.$\newline \bullet$ATP:$\newline$ - ATP is generated during the light reactions through photophosphorylation.$\newline$ - Therefore, ATP is a product of the light reaction.$\newline \bullet$Oxygen:$\newline$ - Oxygen is produced as a byproduct of the splitting of water molecules during the light reactions.$\newline$ - Therefore, oxygen is a product of the light reaction.$\newline$Based on the analysis, the correct answer is Option 2: NADH, as it is not a product of the light reaction of photosynthesis.