Answer :
There were many resources from conquered lands that were a major contributor to Rome's economic growth, but the best option from the list would be "merchants".
Answer:
A. merchants
Explanation:
Roman trade was the engine that led to the economy of the late Republic and early Empire. Fads and trends of historiography and popular culture have tended not to deal with the economic base of the empire in favor of the lingua franca that was Latin and the deeds of the legions. Both the language and the legions were supported by commerce, being at the same time part of its spine. The Romans were businessmen and the longevity of their empire was due to their trade.
Although in theory the members of the Senate and their families were prohibited from engaging in trade, members of the equestrian order did, despite their aristocratic values that emphasized military hobbies and recreational activities. Commoners and freemen had stores or tended to markets, while large numbers of slaves did most of the hard work. The slaves themselves were also the object of commercial transactions, and given their high proportion in society (compared to Ancient Greece) and the reality of the escapes, servile wars and minor uprisings, gave a distinctive touch to Roman trade.
The intricate, complex and extensive accounting of Roman commerce was carried out with the help of counters and Roman abacuses, which used Roman numbers, were specially designed for the accounts in coins and Roman units.