Answer:
d. They thought that their ancestors had the power to help them.
Step-by-step explanation:
Traditional West African cultures believed that the ancestors have the power to bestows luck or curse to the world of living. For example, they believed the ancestors could help them when they're being attacked by the enemy or influenced the weather for good harvest, etc.
It is very common for traditional groups in Africa to offers prayers and/or sacrifice to the dead ancestors with the hope that they will help them rather than against them.