### Solution:
To determine whether the statement "All spheres are similar" is true or false, let us examine the definition of similarity in geometry.
1. Definition of Similarity:
- In geometry, two shapes are said to be similar if they have the same shape but can differ in size. This means that one shape can be obtained from the other by uniformly scaling (enlarging or shrinking).
2. Properties of Spheres:
- A sphere is a perfectly round geometrical object in three-dimensional space, such as the shape of a round ball.
- All spheres have the same shape regardless of their radius. The surface of a sphere is uniform, and its curvature is consistent in every direction from any point on its surface.
3. Similarity of Spheres:
- Given that the only distinguishing factor between different spheres is their size (radius), and because the shape of spheres remains constant, any two spheres are always similar regardless of their size.
- Thus, if you take two spheres with different radii, one can be viewed as a scaled version of the other.
### Conclusion:
Based on the definition of similarity and the properties of spheres, we can say that the statement "All spheres are similar" is indeed true. Therefore, the correct answer is:
0 A. True
