Question

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

Explanation:

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