Ravi's uncle guided him how he ............... attempt his test.

Correct option is B

The correct answer is "should" because it is used to indicate advice or a recommendation. In the given sentence, Ravi's uncle is providing guidance on how Ravi ought to approach his test. "Should" appropriately conveys the sense of obligation or advice in this context.
Information Booster
1. "Should" is used to express suggestions, recommendations, or obligations.
2. It is softer than "must" and is often used in polite contexts.
3. The word "guided" in the sentence implies advice, making "should" the correct fit.
4. "Can" or "will" would not be suitable, as they indicate ability or future certainty, not advice.
5. "May" is used for permission or possibility, which does not align with the context here.
Additional Knowledge
(a) Can: This is used to denote ability or possibility, but it does not imply advice or guidance. Example: "He can complete the task if he starts now." In the given sentence, "can" does not fit as the context involves advice.
(c) May: This indicates permission or likelihood but is inappropriate here, as it does not convey advice. Example: "You may leave the room after the meeting."
(d) Will: This is used to indicate certainty about a future event. It is unsuitable here because the sentence is about guidance, not a definite future action. Example: "He will complete his assignment tomorrow."