**Core Concept**
The action of an intramedullary 'K' nail is a type of internal fixation used in orthopedic surgery to stabilize and align long bones. It involves the insertion of a rod or nail into the medullary canal of the bone to provide support and promote healing.

**Why the Correct Answer is Right**
The intramedullary 'K' nail works by distributing the stress and load across the fracture site, allowing for early mobilization and reducing the risk of implant failure. The nail is typically made of a durable material such as titanium or stainless steel and is inserted into the medullary canal through a small incision. As the bone heals, the nail provides support and stability, allowing the bone to regain its original shape and function.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is not a recognized type of intramedullary nail.
**Option B:** This option is incorrect because it is a type of external fixation device, not an intramedullary nail.
**Option C:** This option is incorrect because it is a type of plate used in orthopedic surgery, not an intramedullary nail.

**Clinical Pearl / High-Yield Fact**
Intramedullary nails are particularly useful in treating fractures of the femur and tibia, as they provide excellent stability and allow for early mobilization, reducing the risk of complications such as deep vein thrombosis and pressure sores.

**Correct Answer: D.**