The famous Buddhist scholar Asvaghosha was a contemporary of Kanishka, who ruled the Kushan Empire in the 2nd century CE. Option 1, Ashoka, is not the correct answer because Ashoka ruled much earlier, in the 3rd century BCE, and was known as a patron of Buddhism, while Asvaghosha lived several centuries later. Option 2, Bindusara, is also not the correct answer because Bindusara was the father of Ashoka and ruled again during an earlier time period. Option 3, Harsha, is not the correct answer as well because Harsha was a ruler from the 7th century CE, several centuries after Asvaghosha`s time. The correct answer is option 4, Kanishka, who was an important patron of Buddhism during his reign and was associated with many notable Buddhist scholars and figures, including Asvaghosha.