## Core Concept
The question pertains to surgical instruments, specifically handheld retractors used in surgical procedures to expose the area of interest. Handheld retractors can be categorized based on their design and functionality, including whether they are self-retaining or require manual holding.

## Why the Correct Answer is Right
Self-retaining retractors are designed with a mechanism to stay in place without the need for a surgeon's hand to hold them, thereby allowing the surgeon to use both hands for other tasks. Examples include the Weitlaner retractor and the Gelpi retractor. On the other hand, handheld retractors like the Deaver retractor, Richardson retractor, and Army-Navy retractor do not have a self-retaining mechanism and need to be manually held in place.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is not specified, but if it refers to a type of self-retaining retractor, then it would be incorrect because the question asks for non-self-retaining retractors.
- **Option B:** Similarly, without specifics, if B represents a self-retaining retractor, it's incorrect for the same reason.
- **Option D:** If D is a self-retaining retractor, then it's incorrect because it does not fit the description of not being self-retaining.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the choice between using a self-retaining retractor versus a handheld retractor depends on the specific needs of the surgical procedure, including the type of tissue being retracted and the necessity for the surgeon to have both hands free.

## Correct Answer: C.