I want to know the answer to the following question:
What was the name of Apollo's sister?
All the background I'm provided with is that "In Hellenistic times, especially during the 3rd century BCE, as Apollo Helios he became identified among Greeks with Helios, Titan god of the sun, and his sister Artemis similarly equated with Selene, Titan goddess of the moon.". Is that enough to answer the question?
Answer: yes