The correct answer is: Only conclusion II follows.
The first statement is “Some swords are sharp.” This means that there exists at least one sword that is sharp. The second statement is “All swords are rusty.” This means that all swords are rusty.
From the first statement, we can conclude that there exists at least one rusty thing that is sharp. This is because the first statement tells us that there exists at least one sword that is sharp, and the second statement tells us that all swords are rusty. However, we cannot conclude that all rusty things are sharp. This is because the second statement only tells us that all swords are rusty, not that all rusty things are swords.
Therefore, only conclusion II follows.