Final answer:
Russet potatoes are white, oval-shaped, high in starch, and are the best type for baking due to their 'starchy' nature, which provides a fluffy texture.
Step-by-step explanation:
The type of potatoes described as white, oval-shaped, high in starch, and best for baking are Russet potatoes. These potatoes contain a high concentration of unbranched polymers of glucose, which classifies them as 'starchy' potatoes and makes them ideal for recipes where a fluffy or creamy texture is desired, such as baked potatoes and mashed potatoes. In contrast, 'waxy' potatoes like Red or Fingerling varieties contain more branched polymers of glucose, helping them retain their shape better during cooking, hence they are more suitable for dishes like potato salads or soups.