Answer:
B. They were worried that the government would put restrictions on the slave trade.
Step-by-step explanation:
At the time of constitutional convention , the northern states were industrialised and were producer of finished goods while the southern states had agricultural economy and imported finished goods from Britain. They were producing tobacco, cotton, rice and were totally dependent on slave labour. They were afraid that if the federal government gets the power to control the interstate commerce then it could ban the slave trade. They would not have been able to maintain the agricultural activities without the slaves.