The most common substrate of respiration is

Explanation

Respiration is the process by which living organisms produce energy. There are different substrates that can be used for respiration, but the most common one is glucose. Glucose is a type of sugar that is broken down during respiration to release energy. The energy released is used for various cellular activities, including movement, growth, and repair. Fats and amino acids can also be used as substrates for respiration, but they are not as commonly used as glucose. Fats are broken down into fatty acids and glucose before they can be used for respiration. Amino acids, on the other hand, are broken down into glucose and other by-products before they can be used for respiration. Sucrose is a type of sugar that is made up of glucose and fructose. It can be broken down into glucose and fructose before it can be used for respiration. However, sucrose is not as commonly used as glucose as a substrate for respiration. Therefore, the correct answer to the question is option C: Glucose. This is the most common substrate for respiration in living organisms.