In a two-dimensional motion, the instantaneous speed of a particle remains constant at a positive value \(v_0.\) Which of the following statements must always be true?
| 1. | The particle has zero acceleration. |
| 2. | The particle’s acceleration is increasing. |
| 3. | The particle’s acceleration always lies in the plane of motion. |
| 4. | The particle necessarily moves in a uniform circular path. |