Which type of reaction is shown in this energy diagram ?

Answer : The correct option is, D.

Explanation :

Activation energy : It is defined as the minimum amount of energy given to the reactant so that it gets converted into products.

Endothermic reaction : It is defined as the chemical reaction in which the energy is absorbed from the surrounding.

In the endothermic reaction, the energy of reactant are less than the energy of product.

Exothermic reaction : It is defined as the chemical reaction in which the energy is released into the surrounding.

In the exothermic reaction, the energy of reactant are more than the energy of product.

From the given options we conclude that the energy diagram shows endothermic reaction because energy is absorbed from the surrounding.

Hence, the correct option is D.