Wave-particle duality tells us that wave and particle models apply to all objects whatever the size, so why don't we observe wave properties in macroscopic objects? because their particle properties forbid us from observing their wave properties. because their wavelength is extremely long (undetectable). because their wavelength is extremely short (undetectable).

The correct choice is Because their wavelength is extremely short (undetectable).

Wave particle duality is the concept in quantum physics that every particle or quantum may be partly described in terms not only of particles, but also of waves. Today, physicists accept the dual nature of light. They say that the light waves are actually packets of photons travelling closely. So on the basis of this concept we can consider particles as waves too but the wavelength of these waves are too short to be measured that is why we cannot observe wave properties in macroscopic objects

Option (a) is the correct answer.

Explanation:

When these two conducting spheres are connected together through a thin wire then charge from the smaller sphere will travel through the wire. And, this charge will continue to travel towards the neutral sphere until the charge on both the spheres will become equal to each other.

For example, charge on small sphere is 5 C then this charge will continue to travel towards the neutral sphere until its charge also becomes equal to 5 C.

Hence, then their potential will also become equal.

Thus, we can conclude that the spheres are connected by a long, thin wire, then after a sufficiently long time the two spheres are at the same potential.