Interjection as a Part of Speech

Introduction:
An interjection is a part of speech that expresses strong emotions or sudden feelings. It is a word or phrase that is typically used to convey surprise, joy, pain, anger, or other intense emotions. Interjections often stand alone and can be punctuated with an exclamation mark or a comma.

Explanation:
Out of the given options, the correct answer is option C, "ouch." Here's why:

Definition of an Interjection:
An interjection is a word or phrase that is used to express a sudden or strong feeling. It is not grammatically related to the other parts of the sentence and can stand alone. Interjections often occur at the beginning of a sentence and are punctuated with an exclamation mark or a comma.

Examples of Interjections:
- Ouch! That hurt.
- Wow, what a beautiful sunset!
- Oh no, I forgot my keys!
- Ah, I finally finished my project.

Analyzing the Options:
a) soon - Soon is an adverb that indicates a time in the near future. It does not express any sudden or strong feeling, so it is not an interjection.
b) when - When is a conjunction used to introduce a question or a clause indicating time. It does not convey any strong emotion, so it is not an interjection.
c) ouch - Ouch is an interjection that expresses sudden pain or discomfort. It stands alone and conveys a strong feeling, making it an example of an interjection.
d) within - Within is a preposition that indicates being inside or not exceeding certain limits. It does not express any strong emotion, so it is not an interjection.

Conclusion:
In conclusion, an interjection is a part of speech used to express sudden or strong emotions. Out of the given options, "ouch" is the only word that fits this definition, making it the correct answer.