Why did free african americans need certificates of freedom?

They could be legally killed or sold.

Explanation:

Free African-Americans required a certificate to verify their freedom because there were many people willing to sell them. Seeing an African American walking around town wasn't common unless they were collecting water or running errand for their owners. So, naturally people grew suspicious.

Also, many runaway slaves could say that they were free. And, there would be no way to verify that if there were no certificates .

Slavery was truly a terrible time.

the california missions began in the late 18th century as an effort to convert native americans to catholicism and expand european territory. there were 21 missions in all, lasting from 1769 until about 1833.   the missions were built by the spanish starting in 1769 in order to “colonize” the territory of alta california. so the missions were important because they were the means of settling california. it also wanted to keep other european countries out of alta california. building settlements along the coast would them meet these goals. missionaries wanted to convert the indians to the roman catholic faith. california indians did much of the work to build missions.

i am sure the answer is d