The role of enzymes in reactions is to Decrease activation energy. Enzymes facilitate chemical reactions by lowering the energy barrier (activation energy) required for the reaction to occur, thus increasing the rate of the reaction.
So, the correct option is (A): Decrease activation energy
The current passing through the battery in the given circuit, is: 
A constant voltage of 50 V is maintained between the points A and B of the circuit shown in the figure. The current through the branch CD of the circuit is :
Enzymes are proteins that help accelerate metabolism or the chemical reactions in our bodies. They build some substances and decompose others. All living creatures have enzymes.
Our bodies naturally build enzymes. But enzymes are also in mass produce products and food.
One of the most important roles of enzymes is to succor digestion. The process of turning the food that we eat into energy is called digestion. For instance, there are enzymes in our saliva, pancreas, stomach, and intestines. They decompose fats, proteins, and carbohydrates. Enzymes make use of these nutrients for growth and cell repair.