What letter is the cross cutting? what letter is the intrusion?
what letter is the original horizontally?

A: Its fertile oases enabled farmers to grow enough food for themselves and for sale.

Explanation: The Arabia region is a region located within the Arabian desert. A desert is an area of extreme heat, often dry weather condition with barren lands that cannot support agriculture and food production. An oases on the other hand is a region of luscious, cultivate-able land within a desert.

Food is one of the most important basic needs of man and hardly can anyone survive without food for more than twenty days. Hence, the presence of oases within the otherwise dry environment of the Arabia region is a major protection against death from hunger.

Taking a closer look at other options, none of them guarantees food supply and income to the Arabia region unlike food production in oases. Hence, the fertile oases is really the most important factor that serves as protection in the region's history.

Correct option: A