**Core Concept**
The question is testing the student's understanding of the biochemical structure of glycogen, specifically the type of linkage found at branch points. Glycogen is a complex carbohydrate stored in the liver and muscles, consisting of long chains of glucose units linked by glycosidic bonds.

**Why the Correct Answer is Right**
The correct answer is due to the presence of alpha-1,6-glycosidic bonds at branch points in glycogen. These bonds are formed by the enzyme glycogen branching enzyme (also known as 1,4-alpha-glucan branching enzyme), which breaks the alpha-1,4-glycosidic bonds between glucose units and re-links them with alpha-1,6-glycosidic bonds, creating branch points in the glycogen molecule. This branching structure allows glycogen to be compactly stored and rapidly mobilized when needed.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not specify the type of glycosidic bond found at branch points in glycogen.
* **Option B:** This option is incorrect because it refers to a different type of glycosidic bond found in other polysaccharides, not glycogen.
* **Option C:** This option is incorrect because it does not accurately describe the type of linkage found at branch points in glycogen.

**Clinical Pearl / High-Yield Fact**
It's worth noting that the glycogen branching enzyme is a key enzyme in glycogen metabolism, and defects in this enzyme can lead to glycogen storage diseases such as glycogen storage disease type IV (Andersen's disease).

**Correct Answer: C. alpha-1,6-glycosidic bonds**