Final answer:
The most commonly grown crop in the savannas of Africa is millet.
Step-by-step explanation:
In the savannas of Africa, the crop that was most commonly grown was millet. Millet is a drought-tolerant crop that thrives in the warm and arid conditions of the savanna. It is a staple crop for many communities in West Africa and is used to make porridge, flatbread, and other food products.