老子在中国传统思想史上的主要贡献表现在：一是提出了抽象的“道”，突出了宇宙的统一性，使中国传统思想从具体思维转向创造性的抽象思维：二是丰富发展了辩证法思想，使辩证思想成为中国古代思想的光荣传统：三是提出了一种逆向思维的模式，使道家思想与儒家思想并立互补，成为中国传统思想的两大主干思想。

A. as to whether medically assisted suicide should be allowed to continue even though it is strictly illegal in the U.S
B. between the expression of a personal choice and a moral obligation
C. over the possible adverse effect of self-determination
D. about the idiosyncratic particularity of suicide