Here's why:
* Nouns are words that name people, places, things, or ideas. "Inspection" is a noun.
* Adjectives describe nouns. "Quality control" modifies the noun "inspection" to specify what kind of inspection it is.
* Noun phrases are groups of words that act as a noun. In this case, "quality control inspection" acts as the subject of the sentence.
Example:
"Quality control inspection is important for ensuring product quality."
In this sentence, "quality control inspection" is the subject, and it's performing the action of being "important."