The correct answer is **A … no article required …the** (Option 4). **Comprehensive Derivation:** The correct answer is 'A … no article required …the'. Explanation & Key Takeaways: • Articles are of three -a, an, the. • 'a' is used before a common noun singular with a consonant sound. • 'an' is used before a common noun singular with a vowel sound. • 'the' is used before a noun whenever it is to be made particular, with a noun that has already been mentioned, with superlatives, with names of countries if it contains a common noun, with a common noun when it represents the whole class. • 'Lubricating oil' is a common noun singular with a consonant sound hence, we use article 'a' before it. • When 'machine' is mentioned for the first time it is being spoken in general but we use 'the' before machine when it's mentioned second time because it is clear from the situation what is being mentioned. • Hence, option 4 is the correct answer. The correct answer is -'A lubricating oil is put on machine parts to make the machine run better'. **Option Elimination:** • **Option 1 (An… no article required … the)**: Incorrect distractor. • **Option 2 (No article required … a … a)**: Incorrect distractor. • **Option 3 (A … no article required … an)**: Incorrect distractor. • **Option 4 (A … no article required …the)**: Correct Answer; accurate according to canonical reference. **Exam Trap:** Be careful of misleading distractors and subtle terminology differences. Verify core properties before selecting your answer. **Memory Booster:** Core mnemonic rule: A … no article required …the corresponds to Option (4).