Six roads lead to a country. They may be indicated by letters X, Y, Z and digits 1, 2, 3. When there is storm, $Y$ is blocked. When there are floods X, 1 and 2 will be affected. When road 1 is blocked, $Z$ also is blocked. At a time when there are Hoods and a storm also blows, which road(s) can be used?

The problem provides specific conditions for which roads are blocked based on weather events. First, let us identify the blocked roads during a storm. The question states that when there is a storm, road Y is blocked. Second, let us identify the blocked roads during floods. The question states that X, 1, and 2 are affected. Additionally, there is a conditional rule: when road 1 is blocked, road Z is also blocked. Since road 1 is blocked by the floods, road Z becomes blocked as well. Now, we list all the roads that are blocked when both a storm and floods occur simultaneously: Road Y is blocked by the storm. Roads X, 1, and 2 are blocked by the floods. Road Z is blocked because road 1 is blocked. The total list of blocked roads is X, Y, Z, 1, and 2. Out of the six original roads (X, Y, Z, 1, 2, 3), the only road remaining that is not affected by either condition is road 3. Therefore, only road 3 can be used. This corresponds to option C.