Answer : The letter represents the activated complex is, B.
Explanation :
Activated complex : When the reactant molecules absorb energy, their bonds are loosened and new loose bonds are formed between them.
The intermediate thus formed is known as an activated complex or it is also known as transition state complex.
It is unstable and immediately dissociates to form the stable products. In the graph, it is present at the higher point.
In the given graph, F represent the reactant energy, B represent the activated complex, G represent the product, Y represent the reactant, C energy of the reaction.
Hence, the activated complex is located at point B.