详解
Choice C is the best answer. Lines 63-65("As...consideration") suggest that the assumption made by gift-givers in lines 41-44("problem...appreciation") may be incorrect. The gift-givers assume that recipients will have a greater appreciation for costly gifts than for less costly gifts, but the authors suggest this relationship may be incorrect, as giftrecipients "may not construe smaller and larger gifts as representing smaller and larger signals of thoughtfulness and consideration" (lines 63-65,"As...consideration").
Choices A and D are incorrect because lines 53-55("Perhaps...consideration") and 75-78("In...relations.") address the question of "why" gift-givers make specific assumptions rather than addressing the validity of these assumptions. Choice B is incorrect because lines 55-60("According...relationship") focus on the reasons people give gifts to others.