once a source of oil has been located, the greatest technological problems involve techniques used…

once a source of oil has been located, the greatest technological problems involve techniques used to\nselect one:\n○ a. extract the oil and get it to the surface.\n○ b. refine it.\n○ c. transport it by railroad.\n○ d. develop tar sands.

once a source of oil has been located, the greatest technological problems involve techniques used to\nselect one:\n○ a. extract the oil and get it to the surface.\n○ b. refine it.\n○ c. transport it by railroad.\n○ d. develop tar sands.

Answer

Brief Explanations:

After locating an oil - source, the primary technological hurdle is extracting the oil and bringing it to the surface, as this involves complex subsurface operations. Refining comes after extraction, transporting by railroad is a later - stage logistical step, and developing tar sands is a different process from basic oil extraction after discovery.

Answer:

A. extract the oil and get it to the surface