The correct answer is: Still
The word “still” is used to indicate that something continues to be true or to happen, even though something else is happening or has happened. In this case, the speaker is saying that they were tired, but they still managed to finish the work.
The other options are not as appropriate in this context. The word “although” is used to introduce a clause that expresses a contrast or concession. In this case, it would be used to say that the speaker was tired, but they managed to finish the work anyway. However, this is not the meaning that the speaker is trying to convey. The word “but” is used to introduce a clause that expresses a contrast or contradiction. In this case, it would be used to say that the speaker was tired, and they did not manage to finish the work. However, this is also not the meaning that the speaker is trying to convey. The word “yet” is used to introduce a clause that expresses a contrast or surprise. In this case, it would be used to say that the speaker was tired, but they managed to finish the work anyway. However, this is not the most natural way to express this meaning.
Therefore, the word “still” is the most appropriate answer.