In which part of the body is glycogen primarily stored?

Glycogen is primarily stored in the liver and muscles, making this the correct answer. In the body, glycogen serves as a readily available source of energy. The liver stores glycogen to help maintain blood glucose levels during fasting or between meals, ensuring that the brain and other vital organs receive adequate energy. Muscles store glycogen primarily for use during physical activity, providing energy for muscle contractions.

The other options do not accurately represent the primary storage sites of glycogen. In plants, carbohydrates are stored as starch, not glycogen. Glycogen is not stored in the bloodstream; instead, glucose circulates in the blood, and glycogen stores are mobilized from the liver and muscles when needed. Adipose tissue, while important for storing fats, does not store glycogen; it stores triglycerides. Thus, the liver and muscle tissue are the specific locations where glycogen is concentrated in the human body.