Jean believes that they should add a low-cost model to their line because even though they dominate the high-cost market, their competitors are selling more units in the lower-end market. So, he believes adding a low-cost model would allow them to increase over sales while continuing to dominate the high end market.
Tracy doesn't think this is a good idea because she thinks that adding a low cost model will put them at a disadvantage in the high-cost market (note that Jean believes this decision will not affect their domination of the high-end market) since their current consumers are those who associate their company with quality and adding a low-cost model will put them on equal footing with their competitors int he high-cost market.
Therefore, Jean and Tracy disagree over whether the company would no longer dominate the high-cost market if it began selling a low-cost model, i.e. answer choice (D).
Hope that clears things up! Please let us know if you have any other questions.
