The correct options are
A Nomadic people started to work in Oil companies
B Development of cities.
C Development of infrastructure.
The discovery of oil and natural gas changed the landscape of Sahara. With the discovery of oil, people started constructing oil wells to extract oil. This led to counties growing richer and cities being built. Superhighways were built to connect large cities. The modern transportation systems replaced camels . More nomadic people started taking up jobs in oil and gas companies.