Given the task definition and input, reply with output. This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

After they each performed, both were deemed equal until Apollo decreed they play and sing at the same time. As Apollo played the lyre, this was easy to do. Marsyas could not do this, as he only knew how to use the flute and could not sing at the same time. Apollo was declared the winner because of this. Apollo flayed Marsyas alive in a cave near Celaenae in Phrygia for his hubris to challenge a god. He then nailed Marsyas' shaggy skin to a nearby pine-tree. Marsyas' blood turned into the river Marsyas.
What instrument did Apolo play?