Light has both a wave and a particle nature. Particles have a wave nature as well, and therefore. A. Their mass is not well defined. B. Their position can not be specified with absolute precision. C. All particles decay with a certain characteristic lifetime. D. Their speeds can only have certain quantized values.

Answer: Their position can not be specified with absolute precision

This is as a consequence of the Heisenberg uncertainty principle enunciated in 1927, after the works of the French physicist Louis De Broglie who proposed the existence of matter waves, that is to say that all matter has a wave associated with it.

The uncertainty principle postulates that the fact that each particle has a wave associated with it, imposes restrictions on the ability to determine its position and speed at the same time.

In other words:

It is impossible to measure simultaneously (according to quantum physics), and with absolute precision, the value of the position and the momentum (linear momentum) of a particle.

So, the greater certainty is seeked in determining the position of a particle, the less is known its linear momentum and, therefore, its mass and velocity.

It should be noted that this uncertainty does not derive from the measurement instruments, but from the measurement itself. Because, even with the most precise devices, the uncertainty in the measurement continues to exist.

Thus, in general, the greater the precision in the measurement of one of these magnitudes, the greater the uncertainty in the measure of the other complementary variable.

This principle is one of the fundamentals of quantum mechanics that differentiates it from Newtonian mechanics, and it is due to this that when particles have a wave behavior, when performing a measurement:

their position can not be specified with absolute precision

Therefore the correct option is B.