I think the correct answer from the choices listed above is option B. A gene is a tightly coiled strands of DNA. A gene is the basic unit of heredity and is made up of DNA. It acts as instructions to make molecules. Hope this answers the question.
In photosynthesis, an electron carrier of the light cycles is the nicotinamide adenine dinucleotide phosphate or NADP. This is the oxidized form, because the reduced form of this carrier has the extra H (NADPH). This is somehow related to the electron carrier called nicotinamide adenine dinucleotide or NAD (minus the phosphate).