An oil field prospector and developer reported a large oil deposit in southwestern Texas. As a result, a large oil and gas company purchased the field with the intention of drilling oil wells in the area soon afterwards. However, the company found that the oil deposit was actually much smaller than the prospector had indicated. Thus, the methods that the prospector had used to determine the size of the oil deposit must have been inaccurate.

Which of the following is an assumption on which the argument depends?

(A) The company’s methods of measuring the size of the oil deposit were determined by a third party to be more accurate than those used by the prospector.
(B) The prospector did not purposefully fabricate or misrepresent the size of the oil deposit.
(C) Though smaller than originally thought, the oil deposit contained enough oil to make drilling commercially feasible.
(D) The prospector did not explore other oil fields and use the same methods to determine the magnitude of the oil present, if any.
(E) The company had successfully drilled for oil in other large oil fields in Texas throughout the early twentieth century.