Areason why slavery developed in the american colonies was?

southern plantation owners needed more labor at lower costs.

Explanation:

After the indentured servants time was up for 4-7 years they were required to work, the owner had to pay them. The indentured servants were given money, food, and a small bit of land. Eventually, there was too much indentured servants to provide for. Plantation owners had to buy slaves so they didn't lose as much money and land. Slaves didn't get land, money, or freedom. While indentured servants were freed after their 4-7 years of working. Sometimes, some people were born into slavery.

the right answer is d