Concept:Stative verbs like ‘know’ describe a state, not an action. They are not used in continuous tenses.Rule / Clue:For third-person singular subjects (she, he, it), simple present tense adds ‘-s’ to the base verb. ‘Know’ should not be in ‘-ing’ form without an auxiliary.Explanation:Option A is wrong because ‘knowing’ alone cannot be the main verb. Option B is wrong because ‘know’ is stative; we do not say ‘is knowing’. Option D uses ‘known’ which is a past participle and needs ‘has’ or ‘had’. Only Option C correctly uses ‘knows’ in simple present tense, following subject-verb agreement and the stative verb rule.Answer:Option C: She knows the answer.