Answer;
C) ATP
Explanation;
-Photosynthesis can be divided into two parts: the light-dependent reactions and the light-independent reactions (also referred to as the "dark" reactions). 
-The two products of the light-dependent reactions of photosystem are ATP and NADPH.  The movement of high energy electrons releases the free energy that is needed to produce these molecules.  The ATP and NADPH are used in the light-independent reactions to make sugar.
-The light-independent reactions, or dark reactions, of photosynthesis are chemical reactions that convert carbon dioxide and other compounds into glucose. These reactions occur in the stroma, the fluid-filled area of a chloroplast outside the thylakoid membranes.
 
        
             
        
        
        
In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell.——————Neurotransmitters are endogenous chemicals that enable neurotransmission. It is a type of chemical messenger which transmits signals across a chemical synapse, such as a neuromuscular junction, from one neuron (nerve cell) to another "target" neuron, muscle cell, or gland cell.
        
             
        
        
        
Because good researchers rely on first hand account or better said primary evidence. The reason why they rely on primary evidence is because it is usually the most reliable. Much more so than secondary or even tertiary evidence. This enables them to understand the history of a certain topic better.