700 level question

Ythex has developed a small diesel engine that produces 30 percent less particulate pollution than the engine made by its main rival, Onez, now widely used in Marania; Ythex's engine is well-suited for use in the thriving warehousing businesses in Marania, although it costs more than the Onez engine. The Maranian government plans to ban within the next two years the use of diesel engines with more than 80 percent of current diesel engine particulate emissions in Marania, and Onez will probably not be able to retool its engine to reduce emissions to reach this target. So if the ban is passed, the Ythex engine ought to sell well in Marania after that time.

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

A. Marania's warehousing and transshipment business buys more diesel engines of any size than other types of engines.
B. Ythex is likely to be able to reduce the cost of its small diesel engine within the next two years.
C. The Maranian government is generally favorable to anti-pollution regulations.
D. The government's ban on high levels of pollution caused by diesel engines, if passed, will not be difficult to enforce.
E. The other manufacturers of small diesel engines in Marania, if there are any, have not produced an engine as popular and clean-running as Ythex's new engine.