In 320 AD, Chandra Gupta I ascended to power, reuniting and strengthening northern India, while the Tamil kingdoms controlled the south. Option D is correct.
Chandragupta I was a king of the Gupta dynasty, who ruled in northern India. He was the first emperor of the dynasty.
The Gupta Empire was an ancient Indian empire lasting from the mid-to-late 3rd century CE to 543 CE.