Final answer:
The hair color of Jason as described by Medea in Ovid's Heroides is not explicitly mentioned, making it impossible to give a definitive answer.
Step-by-step explanation:
According to Medea in Ovid's Heroides, Jason's hair is not explicitly described, making it impossible to definitively answer whether it was blond, black, red, or brown. In classical texts, the appearance of mythological characters like Jason can vary, but in Ovid's Heroides, there is no specific mention of Jason's hair color. Other texts or myths may describe Jason's physical features. However, if this is a question from a specific passage or translation of the Heroides that does mention his hair color, then the answer would be based on that particular version. As a tutor, without the specific passage, I can advise looking directly at the text for any descriptive details about Jason's appearance.