At the sign depicted in the image, what must you do?

Why this is the correct answer

This is the STOP sign (R-2), a red octagonal sign with the word STOP in white letters. It is a priority sign that imposes TWO obligations on the driver: 1. You must ALWAYS stop completely. Bring your vehicle to a full stop at the stop line painted on the road. If there is no stop line, you must stop immediately before the intersection. 2. After stopping, you must give way (yield) to all vehicles travelling on the crossroad you are approaching. Important: the stop is ALWAYS mandatory, regardless of whether there are other vehicles coming or not. Even if the road appears completely empty, you must still come to a complete stop. Simply slowing down is not enough. Why is A correct? Because it states both obligations: always stop AND give way. Why is B wrong? Because it suggests you only need to stop when vehicles are approaching. The stop is mandatory even with no traffic. Why is C wrong? Because it suggests stopping only when visibility is poor. You must stop every time, not just when visibility is limited. Tip: Do not confuse this sign with the "Give Way" (yield) sign (R-1), which is a white inverted triangle with a red border. The yield sign requires you to give way but does NOT always require a complete stop -- you may proceed without stopping if it is safe. The STOP sign always requires a full stop.