Choose the correct sentence.

**The reasoning** This tests **subject-verb agreement with negative contractions**. Here's the rule: For third-person singular subjects (he, she, it), we use **"doesn't"** (does + not) with the **base form** of the main verb. ✓ He **doesn't know** = He does not know The auxiliary verb "does" already carries the "-s" for third person, so the main verb stays in its base form (know, not knows). **Why the wrong options tempt you** **A) "He don't know"** — "Don't" is for I/you/we/they. Many Nigerian English speakers use "don't" everywhere, but formal English requires "doesn't" for he/she/it. **B) "He doesn't knows"** — You're double-marking! Once you add "doesn't," the main verb can't also have "-s". Only one verb gets the third-person marker. **D) "He not know"** — Missing the auxiliary verb entirely. English negatives need "do/does/did" + not (except with "be" and modals). **Quick takeaway** With he/she/it in negative sentences, remember: **doesn't + base verb** — the "-s" lives in "doesn't," so the main verb stays plain.