A:;
B:;
C:;
D:.
下图为甲病(A-a)和乙病(B-b)的遗传系谱图,其中一种病是伴性遗传病,下列相关叙述,正确的是 ( )
在显微镜下观察下列哪一种材料时,能在细胞内找到图中④所示结构?( )
Could you tell me answer to this question? I can't work it out myself.