## **Core Concept**
Sensory receptors can be classified based on their adaptation properties and the area they cover. Adaptation refers to the receptor's ability to respond to a stimulus over time. Receptors with **slow adaptation** or **no adaptation** are responsible for detecting sustained stimuli. The area covered by a receptor, known as its receptive field, varies among different types of sensory receptors.

## **Why the Correct Answer is Right**
The correct answer, **Pacinian corpuscles** are not correct; instead, the focus is on **type I mechanoreceptors or Meissner's corpuscles are not the best fit; the best fit is actually type II, which are known as Merkel's discs or Merkel complexes**. Merkel's discs are slowly adapting type I mechanoreceptors. They have a small receptive field, meaning they have **least coverage** and are responsible for detecting sustained pressure and texture. Their slow adaptation means they **continue to fire as long as the stimulus is present**, which aligns with the description of having **delayed recovery**.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because it is not specified; however, if it referred to a rapidly adapting receptor with a large receptive field like Pacinian corpuscles, it would be incorrect due to its large coverage and rapid adaptation.
- **Option B:** Without specifics, it's hard to address, but if it referred to Meissner's corpuscles, they are rapidly adapting and have a moderate-sized receptive field, not fitting the description.
- **Option D:** Similarly, without specifics, if it suggested a receptor type with rapid adaptation or large coverage, it would not align with the given description.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **Merkel's discs (or Merkel complexes)** are crucial for the sustained detection of pressure and texture. They play a significant role in the ability to perceive form and texture through touch. Their slow adaptation and small receptive fields make them ideal for tasks requiring detailed tactile discrimination.

## **Correct Answer: C. Merkel's discs.**