Two Economists,Adam and Joan,are Discussing the Possibility of Substantially Reforming

Two economists,Adam and Joan,are discussing the possibility of substantially reforming the current federal tax system.Adam thinks the current system is fine,but Joan is in favour of reform.Which statement is the least likely explanation for the disagreement

A) Adam is a positive economist, and Joan is a normative economist.
B) Adam and Joan have different positive views about the effect of changing the tax system.
C) Adam and Joan have different values, and so they have different normative views about policy.
D) Adam is better off under the current system, and Joan would be better off if the reforms were implemented.