(C) Text Classification
Text Classification categorizes documents into predefined groups, which is how spam filters sort emails into "spam" or "not spam" categories.
The textbook defines Text Classification as a tool that "classifies a sentence or document category-wise" into predefined groups. Spam filtering works by classifying incoming emails into categories (spam/not spam), making Text Classification the correct answer. Virtual Assistants relate to voice processing, Sentiment Analysis detects emotions/opinions, and Automatic Summarization condenses text — none of these match spam filtering.