What is a threshold stimulus?

Explanation

**Step-by-Step Solution:**

1. **Definition of Threshold Stimulus**: A threshold stimulus is defined as the minimum intensity of a stimulus that is necessary to elicit a response from an organism.

2. **Understanding Intensity**: The term "intensity" refers to the strength or magnitude of the stimulus. This can be in the form of light, sound, pressure, or any other type of sensory input.

3. **Response Requirement**: For a stimulus to be considered a threshold stimulus, it must be strong enough to trigger a physiological response in a human or an animal. If the stimulus is below this threshold, no response will occur.

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