Which of the following best describes a static body?

A static body is best described as a rigid body that is at rest. In physics, "static" refers to objects that do not move; they are in a state of equilibrium where all forces acting upon them are balanced. This means that the net force on the body is zero, and it does not change its position over time.

When considering the other options, a body colliding with another and deflecting indicates motion and interaction with forces, which contradicts the definition of being static. A body that is decelerating is in the process of changing its speed, moving away from a state of rest. Lastly, a body moving at a uniform velocity along a straight line is also in motion, maintaining a constant speed, which again implies it is not static. Therefore, the definition of a static body aligns perfectly with the description of a rigid body that is at rest.