Answer:
The Mauryan Empire grew as a result of D. It’s leaders conquering small kingdoms across India
Explanation:
"Chandragupta Maurya" was the founder of Mauryan empire. He defeated Nanda dynasty and came to power.
Mauryan had a strong army and also an excellent spy system to make sure of their internal and external securities. They were known for their big economic accomplishment in the country.
Chandragupta conquered most of the northern parts of India and formed a united northern India. They became wealthy through trade. He also set up postal system. Gradually, conquering most of the small kingdoms across India, they became the first largest empire in India.