Explanation:

When the characteristic impedance of a transmission line is equal to the load impedance, it results in a condition known as impedance matching. In this scenario, all the energy sent from the source will be completely absorbed by the load without any reflection or loss. This is why the correct answer is option 'D'.

Here's a detailed explanation of why this is the case:

1. Impedance Matching:
Impedance matching is a technique used in electrical systems to maximize power transfer and minimize reflections. In the context of transmission lines, it involves adjusting the load impedance to match the characteristic impedance of the transmission line.

2. Reflections in Transmission Lines:
When there is a mismatch between the characteristic impedance and the load impedance, a portion of the energy sent from the source is reflected back towards the source. This is due to the mismatch causing impedance discontinuities in the transmission line.

3. Standing Waves:
The reflected energy combines with the incident energy, resulting in standing waves on the transmission line. These standing waves can cause power loss and distortion of the signal.

4. Impedance Matching Benefits:
By matching the load impedance to the characteristic impedance, the reflections are minimized, and the standing waves are eliminated. This allows for maximum power transfer from the source to the load.

5. Energy Absorption:
When the characteristic impedance of the line is equal to the load impedance, there is no impedance mismatch, and all the energy sent from the source is absorbed by the load. Since there are no reflections, the energy does not bounce back towards the source or get lost in the transmission line.

6. Efficient Power Transfer:
This condition ensures that the maximum amount of power is delivered to the load without any loss. It is an ideal scenario for efficient power transfer in transmission lines.

7. Resonance:
The statement mentioned in option 'C' about the system resonating badly is not accurate. Impedance matching does not lead to resonance. Resonance occurs when there are reactive components in the system that can store and release energy cyclically.

To summarize, when the characteristic impedance of a transmission line matches the load impedance, it results in maximum power transfer and no energy loss. All the energy sent from the source is absorbed by the load, making option 'D' the correct answer.