You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Apollo

Context:
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.

Question:
What is said to have turned into the river Marsyas?

Marsyas' blood