In reflex action the reflex arc is formed by

Options

A. Brain - spinal cord - muscles
B. Receptor - spinal cord - muscles
C. Muscles - receptor - muscles
D. Muscles - spinal cord - receptor

Answer

### Step-by-Step Solution:

1. **Understanding Reflex Action**: Reflex action is an automatic and rapid response to a stimulus that is often harmful. It helps protect the body from potential damage.

2. **Components of the Reflex Arc**: The reflex arc is the pathway that the nerve impulses follow during a reflex action. It consists of several key components:
- **Receptor**: This is the sensory organ that detects the harmful stimulus (e.g., skin, eyes).
- **Sensory Neuron (Afferent Neuron)**: This neuron transmits the signal from the receptor to the spinal cord.
- **Interneuron**: Located in the spinal cord, it processes the information and connects the sensory neuron to the motor neuron.
- **Motor Neuron (Efferent Neuron)**: This neuron carries the response signal from the spinal cord to the effector.
- **Effector**: This is the muscle or gland that carries out the response (e.g., muscle contraction or gland secretion).

3. **Pathway of the Reflex Arc**:
- The receptor detects the stimulus and sends a signal through the sensory neuron to the spinal cord.
- The interneuron in the spinal cord processes the information and sends a signal through the motor neuron.
- The motor neuron activates the effector (muscle or gland), resulting in a reflex action.

4. **Conclusion**: The reflex arc is formed by the receptor, sensory neuron, interneuron, motor neuron, and effector. The correct answer to the question is that the reflex arc consists of these components.