Final answer:
The upper speed limit for any object with mass is the speed of light, which is a fundamental constant in physics and the ultimate speed limit according to Einstein's theory of relativity.
Step-by-step explanation:
The upper limit to the speed of an object with mass is not dependent on the mass of the object, nor is it the speed of sound. Instead, it is determined by the speed of light (option d). According to Einstein's theory of relativity, as an object with mass accelerates towards the speed of light, its mass effectively becomes infinite, and it would require infinite energy to reach the speed of light itself. Therefore, no matter the amount of energy applied, a massive object can only approach, but never reach, the speed of light. This concept is consistent with numerous experiments and is a fundamental principle of physics. The speed of light in a vacuum is exactly 299,792,458 meters per second and is the ultimate speed limit for any particle with mass.