Both A and B are correct since the sailing vessel is "stand on" when leeward of another sailing vessel.
Deck
Rules of the Road: BOTH INTERNATIONAL & INLAND When must a sailing vessel keep her course and speed...
Discussing this exam question.
Key word in the question is "must". The sailboat could tack and go astern of another sailboat without breaking a rule as well as ease sails and bear off. If being overtaken you should hold course until the other vessel is clear.