AI0-001 AI Concepts and Foundations Practice Question
A data scientist is building a natural language processing model to classify customer reviews as positive or negative. Which TWO preprocessing steps are most essential before tokenization? (Select two.)
⚠ Common exam trap
CompTIA often tests the ordering of preprocessing steps, and the trap here is that candidates mistakenly believe stemming, lemmatization, or stop word removal should be done before tokenization, when in fact tokenization must come first to split the text into tokens for those later steps to operate on.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Remove punctuation and special characters.
Removing punctuation and special characters (Option B) is essential because tokenizers typically split on whitespace, so punctuation attached to words (e.g., 'great!', 'bad.') would create noisy tokens like 'great!' and 'bad.' instead of clean tokens 'great' and 'bad'. Converting all text to lowercase (Option C) ensures that words like 'Great', 'great', and 'GREAT' are all mapped to the same token, preventing the model from treating them as distinct features and reducing vocabulary size.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Perform stemming or lemmatization.
Why it's wrong here
Stemming is done after tokenization.
- ✓
Remove punctuation and special characters.
Why this is correct
Removing punctuation helps tokens become clean words.
- ✓
Convert all text to lowercase.
Why this is correct
Lowercasing reduces vocabulary and treats words like 'Good' and 'good' identically.
- ✗
Remove stop words from the text.
Why it's wrong here
Stop word removal is done after tokenization.
- ✗
Replace missing values with a placeholder.
Why it's wrong here
Missing value handling is not specific to preprocessing before tokenization.
About these practice questions
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This AI0-001 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the AI0-001 exam.