Which of the following most logically completes the argument?
Utrania was formerly a major petroleum exporter, but in recent decades economic stagnation and restrictive regulations inhibited investment in new oil fields. In consequence, Utranian oil exports dropped steadily as old fields became depleted. Utrania's currently improving economic situation, together with less-restrictive regulations, will undoubtedly result in the rapid development of new fields. However, it would be premature to conclude that the rapid development of new fields will result in higher oil exports, because __________.
the price of oil is expected to remain relatively stable over the next several years
the improvement in the economic situation in Utrania is expected to result in a dramatic increase in the proportion of Utranians who own automobiles
most of the investment in new oil fields in Utrania is expected to come from foreign sources
new technology is available to recover oil from old oil fields formerly regarded as depleted
many of the new oil fields in Utrania are likely to be as productive as those that were developed during the period when Utrania was a major oil exporter