单选题 Although it rules that these is no constitutional right to physician-assisted suicide, the Court in effect supported the medical principle of "double effect", a ______ moral principle holding that an action having two effects—a good one that is intended and a harmful one that is foreseen—is permissible if the actor intends only the good effect.
A. century's old B. century old C. centuries's old D. centuries-old

【正确答案】 A
【答案解析】[解析] 由于名词不能直接修饰名词,century加上's,变成“长达一个世纪的”,空白处为定语,修饰principle,由空白处前面的a可知century为单数,排除C和D选项。因此,A选项正确。