The correct answer is: D. All of the above
The time of collision is the duration of the physical contact between two objects. The period of collision is the time interval between the initial contact of the two objects and the final separation of the two objects. The period of impact is the time interval between the initial contact of the two objects and the time when the relative velocity of the two objects is zero.
In general, the time of collision, the period of collision, and the period of impact are all the same. However, there are some cases where they may be different. For example, if the two objects are perfectly elastic, then the time of collision will be equal to the period of collision, but the period of impact will be zero. This is because the relative velocity of the two objects will be zero at the moment of contact, but it will not remain zero for the entire duration of the contact.
In other cases, the time of collision may be longer than the period of collision. This can happen if the two objects are not perfectly elastic, or if there is some other force acting on the objects during the collision. For example, if the two objects are colliding in a viscous fluid, then the fluid will exert a drag force on the objects, which will slow them down and prolong the collision.
The period of impact is always less than or equal to the time of collision. This is because the relative velocity of the two objects must be zero at the moment of contact, but it may not be zero for the entire duration of the contact.